Why can nobody overtake?

Why can nobody overtake?

Author
Discussion

Deranged Rover

3,406 posts

75 months

Friday 10th March 2023
quotequote all
Driving home from work last night on my usual country B-road when I found myself behind a Zafira that was in turn behind a tractor doing 20mph or so. No worries, there's a straight coming up and, when we get to it, the entire length of it is clear - more than enough for about 5 or 6 of us to overtake if necessary but luckily, it was only the Zafira and me.

Well, Zafira indicates and pulls out - good stuff, i think, i shall follow suit. Except that said Zafira then proceeded to accelerate ferociously to about 22mph and take the entire length of the straight section to overtake - I quickly realised what was going on and had to pull back in behind the tractor. Zafira then proceeds to pootle along in front of the tractor and only ends up a hundred yards or so in front of it by the time we hit the traffic lights a few miles later.

Obviosuly it was a Zafira so my expectations of driving standards were pretty low, but even I didn't expect this!

Evil.soup

3,595 posts

206 months

Friday 10th March 2023
quotequote all
457892345 said:
Evil.soup said:
I would say its more an issue of clown overtaking in a car that doesn't have the pace to pass in such a short distance. Don't forget, the car they are passing could well be doing 40 to 50 so to pass safely in that space you would need something pretty quick. I can't tell for sure, but is it a MK5 Golf, possibly a GTi, but has the wrong wheels to be a GTi, so probably not even that.

Given that 5 Alive has just come around a blind bend onto that stretch of open bend, this Golf was just chancing his luck in hope that nobody else was coming. A quicker car would have been passed safely by this point.
So we are all agreed? That everyone should have 200bhp/ton or greater? as a matter of safety of course!
Indeed, always been a strong believer in the safety benefits of power!

I have owned a WRX for 17 years and I drive a Ceed as a daily. Sometimes when driving the Ceed I forget where I am and go for an overtake and have often felt I needed a fair bit more grunt to make my drive a safer one lol!

Evil.soup

3,595 posts

206 months

Friday 10th March 2023
quotequote all
Deranged Rover said:
Driving home from work last night on my usual country B-road when I found myself behind a Zafira that was in turn behind a tractor doing 20mph or so. No worries, there's a straight coming up and, when we get to it, the entire length of it is clear - more than enough for about 5 or 6 of us to overtake if necessary but luckily, it was only the Zafira and me.

Well, Zafira indicates and pulls out - good stuff, i think, i shall follow suit. Except that said Zafira then proceeded to accelerate ferociously to about 22mph and take the entire length of the straight section to overtake - I quickly realised what was going on and had to pull back in behind the tractor. Zafira then proceeds to pootle along in front of the tractor and only ends up a hundred yards or so in front of it by the time we hit the traffic lights a few miles later.

Obviosuly it was a Zafira so my expectations of driving standards were pretty low, but even I didn't expect this!
I have been there a few times, you make the assumption that the person in front would maybe consider using full throttle rather than one third. The really crazy thinking with these types is that they don't want to drive too quickly as it's just too dangerous, so they tootle in the oncoming lane and leave you hanging, insane!!

mac96

3,791 posts

144 months

Friday 10th March 2023
quotequote all
Evil.soup said:
Deranged Rover said:
Driving home from work last night on my usual country B-road when I found myself behind a Zafira that was in turn behind a tractor doing 20mph or so. No worries, there's a straight coming up and, when we get to it, the entire length of it is clear - more than enough for about 5 or 6 of us to overtake if necessary but luckily, it was only the Zafira and me.

Well, Zafira indicates and pulls out - good stuff, i think, i shall follow suit. Except that said Zafira then proceeded to accelerate ferociously to about 22mph and take the entire length of the straight section to overtake - I quickly realised what was going on and had to pull back in behind the tractor. Zafira then proceeds to pootle along in front of the tractor and only ends up a hundred yards or so in front of it by the time we hit the traffic lights a few miles later.

Obviosuly it was a Zafira so my expectations of driving standards were pretty low, but even I didn't expect this!
I have been there a few times, you make the assumption that the person in front would maybe consider using full throttle rather than one third. The really crazy thinking with these types is that they don't want to drive too quickly as it's just too dangerous, so they tootle in the oncoming lane and leave you hanging, insane!!
I think the lesson here is really that following someone else into an overtake is just a bad idea and it is always best to let them get clear before you overtake; as you have illustrated, you don't know what they will do- apart from overtaking very slowly there are other bad possibilities such as not pulling in promptly (so hiding a hazard from your view) pulling in and slowing down so that the space you intended to go for isn't there, or bottling out and aborting the overtake half way through leaving the follower in emergency braking.

havoc

30,083 posts

236 months

Friday 10th March 2023
quotequote all
457892345 said:
So we are all agreed? That everyone should have 200bhp/ton or greater? as a matter of safety of course!
No.

The muppets are dangerous enough with stboxes. Give them a ton more torque (which is what 200bhp/tonne would come with in the current world of turbos and EVs) and a tickle on the accelerator could see them straight through the neighbour's shrubbery and into the front room.

That's something I am a little concerned about with the move to EVs - they've all got this ridiculous step-off torque which means any one of them can rival a hot hatch off the traffic lights. Which brings three problems:-
- Road Captains who feel you should stay behind them. Give 'em an EV and you'll need a supercar to safely pass them.
- Doddering Derek and Doris, who from time to time panic and get the pedals confused. A jab on the accelerator by mistake in a Yaris* doesn't do a lot. A jab on the accelerator by mistake in an EV with more power and a lot more torque will see them hit warp speed before they realise their mistake.
- Teenage (and older) boy racers - the sort who would struggle to control anything more spicy than a Citroen C1 yet think they're Max Verstappen - suddenly faced with all that power. Ragging an Insurance Group-3 or -4 hatchback off the lights wouldn't even worry a Transit driver, but an EV is another league.
(Actually, off-topic, what ARE insurance companies going to do when it's EVs as far as the eye can see? Graduated licences? Switchable power modes?)




* Usually. The old boy who managed to shove his Yaris up a kerb, across a lawn and straight through the MiL's bedroom wall (ground-floor retirement apartment) 6 years ago clearly was trying harder. That was a Yaris...if he'd had an EV he'd probably have reached the lounge...where the MiL was sitting.

Deranged Rover

3,406 posts

75 months

Friday 10th March 2023
quotequote all
mac96 said:
I think the lesson here is really that following someone else into an overtake is just a bad idea and it is always best to let them get clear before you overtake; as you have illustrated, you don't know what they will do- apart from overtaking very slowly there are other bad possibilities such as not pulling in promptly (so hiding a hazard from your view) pulling in and slowing down so that the space you intended to go for isn't there, or bottling out and aborting the overtake half way through leaving the follower in emergency braking.
Absolutely - you're quite right and I shall be wary of this (and Zafiras) in future.

When i was taught to drive, my instructor told me that one of the key aspects of overtaking is to spend as little time as possible on the wrong side of the road. I just assumed that everyone else had also been taught this!

cerb4.5lee

30,711 posts

181 months

Friday 10th March 2023
quotequote all
mac96 said:
Evil.soup said:
Deranged Rover said:
Driving home from work last night on my usual country B-road when I found myself behind a Zafira that was in turn behind a tractor doing 20mph or so. No worries, there's a straight coming up and, when we get to it, the entire length of it is clear - more than enough for about 5 or 6 of us to overtake if necessary but luckily, it was only the Zafira and me.

Well, Zafira indicates and pulls out - good stuff, i think, i shall follow suit. Except that said Zafira then proceeded to accelerate ferociously to about 22mph and take the entire length of the straight section to overtake - I quickly realised what was going on and had to pull back in behind the tractor. Zafira then proceeds to pootle along in front of the tractor and only ends up a hundred yards or so in front of it by the time we hit the traffic lights a few miles later.

Obviosuly it was a Zafira so my expectations of driving standards were pretty low, but even I didn't expect this!
I have been there a few times, you make the assumption that the person in front would maybe consider using full throttle rather than one third. The really crazy thinking with these types is that they don't want to drive too quickly as it's just too dangerous, so they tootle in the oncoming lane and leave you hanging, insane!!
I think the lesson here is really that following someone else into an overtake is just a bad idea and it is always best to let them get clear before you overtake; as you have illustrated, you don't know what they will do- apart from overtaking very slowly there are other bad possibilities such as not pulling in promptly (so hiding a hazard from your view) pulling in and slowing down so that the space you intended to go for isn't there, or bottling out and aborting the overtake half way through leaving the follower in emergency braking.
I've been caught out like this before as well, so I avoid following slow cars now when it comes to overtaking and I just leave them to it.

I don't know what it is about Zafiras, but I followed one once on an overtake on a lovely long clear road and he stayed on the other side of road and he wouldn't pull in to let me pass, and he just stayed on the other side of the road. Odd behaviour I thought.

mac96

3,791 posts

144 months

Friday 10th March 2023
quotequote all
Deranged Rover said:
mac96 said:
I think the lesson here is really that following someone else into an overtake is just a bad idea and it is always best to let them get clear before you overtake; as you have illustrated, you don't know what they will do- apart from overtaking very slowly there are other bad possibilities such as not pulling in promptly (so hiding a hazard from your view) pulling in and slowing down so that the space you intended to go for isn't there, or bottling out and aborting the overtake half way through leaving the follower in emergency braking.
Absolutely - you're quite right and I shall be wary of this (and Zafiras) in future.

When i was taught to drive, my instructor told me that one of the key aspects of overtaking is to spend as little time as possible on the wrong side of the road. I just assumed that everyone else had also been taught this!
You were lucky to be taught anything about overtaking!

mac96

3,791 posts

144 months

Friday 10th March 2023
quotequote all
cerb4.5lee said:
mac96 said:
Evil.soup said:
Deranged Rover said:
Driving home from work last night on my usual country B-road when I found myself behind a Zafira that was in turn behind a tractor doing 20mph or so. No worries, there's a straight coming up and, when we get to it, the entire length of it is clear - more than enough for about 5 or 6 of us to overtake if necessary but luckily, it was only the Zafira and me.

Well, Zafira indicates and pulls out - good stuff, i think, i shall follow suit. Except that said Zafira then proceeded to accelerate ferociously to about 22mph and take the entire length of the straight section to overtake - I quickly realised what was going on and had to pull back in behind the tractor. Zafira then proceeds to pootle along in front of the tractor and only ends up a hundred yards or so in front of it by the time we hit the traffic lights a few miles later.

Obviosuly it was a Zafira so my expectations of driving standards were pretty low, but even I didn't expect this!
I have been there a few times, you make the assumption that the person in front would maybe consider using full throttle rather than one third. The really crazy thinking with these types is that they don't want to drive too quickly as it's just too dangerous, so they tootle in the oncoming lane and leave you hanging, insane!!
I think the lesson here is really that following someone else into an overtake is just a bad idea and it is always best to let them get clear before you overtake; as you have illustrated, you don't know what they will do- apart from overtaking very slowly there are other bad possibilities such as not pulling in promptly (so hiding a hazard from your view) pulling in and slowing down so that the space you intended to go for isn't there, or bottling out and aborting the overtake half way through leaving the follower in emergency braking.
I've been caught out like this before as well, so I avoid following slow cars now when it comes to overtaking and I just leave them to it.

I don't know what it is about Zafiras, but I followed one once on an overtake on a lovely long clear road and he stayed on the other side of road and he wouldn't pull in to let me pass, and he just stayed on the other side of the road. Odd behaviour I thought.
That's because he was going quite fast enough for anyone, and if you wanted to overtake him you must be an ABSOLUTE LUNATIC! He was saving you from yourself...


cerb4.5lee

30,711 posts

181 months

Friday 10th March 2023
quotequote all
mac96 said:
Deranged Rover said:
mac96 said:
I think the lesson here is really that following someone else into an overtake is just a bad idea and it is always best to let them get clear before you overtake; as you have illustrated, you don't know what they will do- apart from overtaking very slowly there are other bad possibilities such as not pulling in promptly (so hiding a hazard from your view) pulling in and slowing down so that the space you intended to go for isn't there, or bottling out and aborting the overtake half way through leaving the follower in emergency braking.
Absolutely - you're quite right and I shall be wary of this (and Zafiras) in future.

When i was taught to drive, my instructor told me that one of the key aspects of overtaking is to spend as little time as possible on the wrong side of the road. I just assumed that everyone else had also been taught this!
You were lucky to be taught anything about overtaking!
My Dad always used to overtake as quickly as possible(he had fairly quick cars for the time), so I think that I just picked that up from him. I also picked up racing other cars from him when the opportunity arises as well! hehe However that just doesn't seem to happen much at all now though(I guess speed cameras/traffic volume etc puts people off now). I used to have loads of fun years ago to be fair. driving


cerb4.5lee

30,711 posts

181 months

Friday 10th March 2023
quotequote all
mac96 said:
cerb4.5lee said:
mac96 said:
Evil.soup said:
Deranged Rover said:
Driving home from work last night on my usual country B-road when I found myself behind a Zafira that was in turn behind a tractor doing 20mph or so. No worries, there's a straight coming up and, when we get to it, the entire length of it is clear - more than enough for about 5 or 6 of us to overtake if necessary but luckily, it was only the Zafira and me.

Well, Zafira indicates and pulls out - good stuff, i think, i shall follow suit. Except that said Zafira then proceeded to accelerate ferociously to about 22mph and take the entire length of the straight section to overtake - I quickly realised what was going on and had to pull back in behind the tractor. Zafira then proceeds to pootle along in front of the tractor and only ends up a hundred yards or so in front of it by the time we hit the traffic lights a few miles later.

Obviosuly it was a Zafira so my expectations of driving standards were pretty low, but even I didn't expect this!
I have been there a few times, you make the assumption that the person in front would maybe consider using full throttle rather than one third. The really crazy thinking with these types is that they don't want to drive too quickly as it's just too dangerous, so they tootle in the oncoming lane and leave you hanging, insane!!
I think the lesson here is really that following someone else into an overtake is just a bad idea and it is always best to let them get clear before you overtake; as you have illustrated, you don't know what they will do- apart from overtaking very slowly there are other bad possibilities such as not pulling in promptly (so hiding a hazard from your view) pulling in and slowing down so that the space you intended to go for isn't there, or bottling out and aborting the overtake half way through leaving the follower in emergency braking.
I've been caught out like this before as well, so I avoid following slow cars now when it comes to overtaking and I just leave them to it.

I don't know what it is about Zafiras, but I followed one once on an overtake on a lovely long clear road and he stayed on the other side of road and he wouldn't pull in to let me pass, and he just stayed on the other side of the road. Odd behaviour I thought.
That's because he was going quite fast enough for anyone, and if you wanted to overtake him you must be an ABSOLUTE LUNATIC! He was saving you from yourself...
yes

I think a few people just haven't experienced fairly fast cars, and they just don't understand how capable they can be in comparison to the more normal stuff I reckon. I'm always looking in my rear view looking out for faster stuff on motorways/dual carriageways for example, because I know how quick some cars can be. Whereas if you've never had a quick car then you won't be looking out/or expecting them I reckon.

RVB

1,985 posts

82 months

Friday 10th March 2023
quotequote all
LJF_97 said:
Had mine for 7 years now, although the battery needs to be replaced.
How long has the battery been faulty? Some years, I suspect.

With a defective battery it won't be saving the last video clip before it shuts down (you'll just end up with a corrupt file, and risk of damage to the memory card) because a dashcam needs a good, working battery to power the cam for several seconds after the car cuts the 12v supply, so the cam can finish writing the 'in progress' file to the memory card.

Supercapacitors tend to be vastly longer-lived and more reliable than batteries (and safer - sometimes ageing/defective Li-po batteries catch fire in hot cars).
Cams such as the earlier-mentioned Street Guardian or Viofo generally use supercaps, and they also have carefully thought out and tested designs with better quality components within the cam. Hence a long, reliable service life.

kuiper

207 posts

128 months

Friday 10th March 2023
quotequote all
havoc said:
No.

The muppets are dangerous enough with stboxes. Give them a ton more torque (which is what 200bhp/tonne would come with in the current world of turbos and EVs) and a tickle on the accelerator could see them straight through the neighbour's shrubbery and into the front room.

That's something I am a little concerned about with the move to EVs - they've all got this ridiculous step-off torque which means any one of them can rival a hot hatch off the traffic lights. Which brings three problems:-
- Road Captains who feel you should stay behind them. Give 'em an EV and you'll need a supercar to safely pass them.
- Doddering Derek and Doris, who from time to time panic and get the pedals confused. A jab on the accelerator by mistake in a Yaris* doesn't do a lot. A jab on the accelerator by mistake in an EV with more power and a lot more torque will see them hit warp speed before they realise their mistake.
- Teenage (and older) boy racers - the sort who would struggle to control anything more spicy than a Citroen C1 yet think they're Max Verstappen - suddenly faced with all that power. Ragging an Insurance Group-3 or -4 hatchback off the lights wouldn't even worry a Transit driver, but an EV is another league.
(Actually, off-topic, what ARE insurance companies going to do when it's EVs as far as the eye can see? Graduated licences? Switchable power modes?)




* Usually. The old boy who managed to shove his Yaris up a kerb, across a lawn and straight through the MiL's bedroom wall (ground-floor retirement apartment) 6 years ago clearly was trying harder. That was a Yaris...if he'd had an EV he'd probably have reached the lounge...where the MiL was sitting.
Funnily enough I was pondering exactly this the other day when looking at an Autocar article on the 'new' AR Giulia which will have like 450bhp in standard form, 750 for veloce and 1000+ for QV. It's not something I've really seen being discussed, but I could be wrong.

The current Petrol QV is fast enough, and probably by far TOO fast for the vast majority of drivers. If i'd had mine when I was 17 or 18, I would probably be dead. It's probably not an unreasonable statement to say the majority of the driving public care not a jot about the skill of driving, and even for those who do it's fair to say that perceived ability /= actual skill. I'm generalising massively here, but with a few exceptions for YouTube stars and rappers I would wager most people who drive properly fast cars have worked their way up through a lot of lowered powered stuff to be able to handle the pace on offer.

We're about to wander into an environment where white goods day to day EV's are being sold on the basis of frankly ridiculous power outputs and instant massive torque, and I don't think for one second that the general public's driving skills are anything like up to it. Putting 500+ hp outputs alongside fairly basic chassis design into the hands of new drivers, old drivers, the sort of doris that just potters to the shops in her Zafira etc etc is going to be - imho, very dangerous.

You only need to look at the moose test for the Smart Brabus 1 for a very good example of why this is bad. Currently high power usually comes with a much more developed car and is bought by a driver with at least 'good' ability - it's going to come on everything with a far less capable vehicle and actively marketed to people that shouldn't have that much power under their right foot.


Edited by kuiper on Friday 10th March 13:18

cerb4.5lee

30,711 posts

181 months

Friday 10th March 2023
quotequote all
I've driven a couple of EVs and much to my surprise they were both slow, however in my head I was expecting them to be rocketships because of the instant torque/instant throttle response that I read so much about. However I've now realised that much like performance cars and none performance cars there are both fast and slow EVs. So I'd imagine that the quicker ones will be more to insure, much like the high performance ICE cars are more to insure versus the none performance cars.

They thing with the slower EVs is that they do shoot off the line pretty briskly, but they soon run out of legs though, plus they also have much lower top speeds in comparison to ICE cars as well.

bigothunter

11,297 posts

61 months

Friday 10th March 2023
quotequote all
cerb4.5lee said:
I've driven a couple of EVs and much to my surprise they were both slow, however in my head I was expecting them to be rocketships because of the instant torque/instant throttle response that I read so much about. However I've now realised that much like performance cars and none performance cars there are both fast and slow EVs. So I'd imagine that the quicker ones will be more to insure, much like the high performance ICE cars are more to insure versus the none performance cars.

They thing with the slower EVs is that they do shoot off the line pretty briskly, but they soon run out of legs though, plus they also have much lower top speeds in comparison to ICE cars as well.
We need Intelligent Acceleration Assist alongside Intelligent Speed Assist with Remote Override for good measure rofl

TarquinMX5

1,955 posts

81 months

Friday 10th March 2023
quotequote all
cerb4.5lee said:
They thing with the slower EVs is that they do shoot off the line pretty briskly, but they soon run out of legs
juice though, plus they also have much lower top speeds in comparison to ICE cars as well.

TarquinMX5

1,955 posts

81 months

Friday 10th March 2023
quotequote all
bigothunter said:
We need Intelligent Acceleration Assist alongside Intelligent Speed Assist with Remote Override for good measure rofl
And Non-Intelligent Driver Assist (if they could keep up with demand)

Evil.soup

3,595 posts

206 months

Friday 10th March 2023
quotequote all
kuiper said:
havoc said:
No.

The muppets are dangerous enough with stboxes. Give them a ton more torque (which is what 200bhp/tonne would come with in the current world of turbos and EVs) and a tickle on the accelerator could see them straight through the neighbour's shrubbery and into the front room.

That's something I am a little concerned about with the move to EVs - they've all got this ridiculous step-off torque which means any one of them can rival a hot hatch off the traffic lights. Which brings three problems:-
- Road Captains who feel you should stay behind them. Give 'em an EV and you'll need a supercar to safely pass them.
- Doddering Derek and Doris, who from time to time panic and get the pedals confused. A jab on the accelerator by mistake in a Yaris* doesn't do a lot. A jab on the accelerator by mistake in an EV with more power and a lot more torque will see them hit warp speed before they realise their mistake.
- Teenage (and older) boy racers - the sort who would struggle to control anything more spicy than a Citroen C1 yet think they're Max Verstappen - suddenly faced with all that power. Ragging an Insurance Group-3 or -4 hatchback off the lights wouldn't even worry a Transit driver, but an EV is another league.
(Actually, off-topic, what ARE insurance companies going to do when it's EVs as far as the eye can see? Graduated licences? Switchable power modes?)




* Usually. The old boy who managed to shove his Yaris up a kerb, across a lawn and straight through the MiL's bedroom wall (ground-floor retirement apartment) 6 years ago clearly was trying harder. That was a Yaris...if he'd had an EV he'd probably have reached the lounge...where the MiL was sitting.
Funnily enough I was pondering exactly this the other day when looking at an Autocar article on the 'new' AR Giulia which will have like 450bhp in standard form, 750 for veloce and 1000+ for QV. It's not something I've really seen being discussed, but I could be wrong.

The current Petrol QV is fast enough, and probably by far TOO fast for the vast majority of drivers. If i'd had mine when I was 17 or 18, I would probably be dead. It's probably not an unreasonable statement to say the majority of the driving public care not a jot about the skill of driving, and even for those who do it's fair to say that perceived ability /= actual skill. I'm generalising massively here, but with a few exceptions for YouTube stars and rappers I would wager most people who drive properly fast cars have worked their way up through a lot of lowered powered stuff to be able to handle the pace on offer.

We're about to wander into an environment where white goods day to day EV's are being sold on the basis of frankly ridiculous power outputs and instant massive torque, and I don't think for one second that the general public's driving skills are anything like up to it. Putting 500+ hp outputs alongside fairly basic chassis design into the hands of new drivers, old drivers, the sort of doris that just potters to the shops in her Zafira etc etc is going to be - imho, very dangerous.

You only need to look at the moose test for the Smart Brabus 1 for a very good example of why this is bad. Currently high power usually comes with a much more developed car and is bought by a driver with at least 'good' ability - it's going to come on everything with a far less capable vehicle and actively marketed to people that shouldn't have that much power under their right foot.


Edited by kuiper on Friday 10th March 13:18
You could well be right...

A few weeks ago I was overtaking an MG EV of some sort along a 300m duel carriageway, so I just popped out and gave it half throttle maybe. It was very clear that the fella in the EV wanted to try to prove some kind of point as he floored it to try to stop me passing. Full throttle left him behind me, but it did seem to pick up quickly, until we got close to the round about and he clearly had to jump on the ankers hard and dropped right back. It seems the barges can do straight lines but not corners, so I can see someone very quickly getting themselves into big trouble.

bigothunter

11,297 posts

61 months

Friday 10th March 2023
quotequote all
TarquinMX5 said:
bigothunter said:
We need Intelligent Acceleration Assist alongside Intelligent Speed Assist with Remote Override for good measure rofl
And Non-Intelligent Driver Assist (if they could keep up with demand)
Get dheads off the road. Fully autonomous cars thumbup

MKnight702

3,110 posts

215 months

Friday 10th March 2023
quotequote all
cerb4.5lee said:
mac96 said:
Evil.soup said:
Deranged Rover said:
Driving home from work last night on my usual country B-road when I found myself behind a Zafira that was in turn behind a tractor doing 20mph or so. No worries, there's a straight coming up and, when we get to it, the entire length of it is clear - more than enough for about 5 or 6 of us to overtake if necessary but luckily, it was only the Zafira and me.

Well, Zafira indicates and pulls out - good stuff, i think, i shall follow suit. Except that said Zafira then proceeded to accelerate ferociously to about 22mph and take the entire length of the straight section to overtake - I quickly realised what was going on and had to pull back in behind the tractor. Zafira then proceeds to pootle along in front of the tractor and only ends up a hundred yards or so in front of it by the time we hit the traffic lights a few miles later.

Obviosuly it was a Zafira so my expectations of driving standards were pretty low, but even I didn't expect this!
I have been there a few times, you make the assumption that the person in front would maybe consider using full throttle rather than one third. The really crazy thinking with these types is that they don't want to drive too quickly as it's just too dangerous, so they tootle in the oncoming lane and leave you hanging, insane!!
I think the lesson here is really that following someone else into an overtake is just a bad idea and it is always best to let them get clear before you overtake; as you have illustrated, you don't know what they will do- apart from overtaking very slowly there are other bad possibilities such as not pulling in promptly (so hiding a hazard from your view) pulling in and slowing down so that the space you intended to go for isn't there, or bottling out and aborting the overtake half way through leaving the follower in emergency braking.
I've been caught out like this before as well, so I avoid following slow cars now when it comes to overtaking and I just leave them to it.

I don't know what it is about Zafiras, but I followed one once on an overtake on a lovely long clear road and he stayed on the other side of road and he wouldn't pull in to let me pass, and he just stayed on the other side of the road. Odd behaviour I thought.
The Zafailure is driven, almost exclusively, by those that have lost at life and wish to take it out on everyone else.