A little PH experiment I would like your help with
Discussion
kambites said:
RobM77 said:
Measuring the Lotus is much harder as it can only be done between fill ups, which I rarely do in such a light car.
Get a bluetooth OBD reader. Then you can get your smartphone to show instantaneous and trip MPG as well as just about everything else the ECU is measuring. You can even tie it into the GPS on your phone to log MPG by location, speed, throttle position, or whatever else you want. They only cost about a fiver.
I did crunch the numbers once between fill ups though and I think I do about 15-20mpg on the way to a track day and around 4 to 5mpg on track.RobM77 said:
To be honest I'm really not that interested I did crunch the numbers once between fill ups though and I think I do about 15-20mpg on the way to a track day and around 4 to 5mpg on track.
Fair enough. I did crunch the numbers once between fill ups though and I think I do about 15-20mpg on the way to a track day and around 4 to 5mpg on track.I found it fascinating to be able to see exactly what the engine was doing under what circumstances.
kambites said:
RobM77 said:
To be honest I'm really not that interested I did crunch the numbers once between fill ups though and I think I do about 15-20mpg on the way to a track day and around 4 to 5mpg on track.
Fair enough. I did crunch the numbers once between fill ups though and I think I do about 15-20mpg on the way to a track day and around 4 to 5mpg on track.I found it fascinating to be able to see exactly what the engine was doing under what circumstances.
RobM77 said:
My understanding of 'extra urban' as far as official mpg figures go is that it's a mixture of driving in a non urban setting. The definition will be somewhere on the web, but I think it involves a bit of motorway, a bit of A road, some stop start etc. Generally it defines most of my driving around my local area, but I average about 48mpg for that. I don't think the EU figures allow for 1 lepton B road driving and frequent sideways action though 
I think IM right on this. They are quoted:Urban (local): 40mpg Extra Urban(motorway): 60 mpg and Combined(self explanatory): 48 mpg
blindswelledrat said:
RobM77 said:
My understanding of 'extra urban' as far as official mpg figures go is that it's a mixture of driving in a non urban setting. The definition will be somewhere on the web, but I think it involves a bit of motorway, a bit of A road, some stop start etc. Generally it defines most of my driving around my local area, but I average about 48mpg for that. I don't think the EU figures allow for 1 lepton B road driving and frequent sideways action though
I think IM right on this. They are quoted:Urban (local): 40mpg Extra Urban(motorway): 60 mpg and Combined(self explanatory): 48 mpg
http://www.dft.gov.uk/vca/fcb/faqs-fuel-consumptio...
"Extra-Urban Cycle
This cycle is conducted immediately following the urban cycle and consists of roughly half steady-speed driving and the remainder accelerations, decelerations, and some idling. Maximum speed is 75mph (120km/h), average speed is 39mph (63 km/h) and the distance covered is 4.3miles (7km). "
blindswelledrat said:
Manufacturers MPG figures they often bear little relation to your own driving.
Indeed. This isn't new and shouldn't surprise anyone. Unfortunately if anyone buys a car and expects it to do its advertised MPG then I think they are a bit naiive.So the manufacturers claimed MPG is not a real world MPG. So what's the point? The point is so that you can COMPARE cars against each other. If car A claims 60mpg and car B claims 40mpg then although you're unlikely to achieve EITHER of those figures, you do at least know that car B will be less efficient than car A.
80'ish seems to be a figure that my O/H's 1.3 Ka starts to even out against my 4.0 S Type. Below that, her's pisses all over mine for mpg, but there's quite a big drop off on hers as soon as it's keeping up with motorway traffic. The gearing mostly I'd suspect, mine's sitting at just over 2k, hers around 3,5k
mrmr96 said:
. If car A claims 60mpg and car B claims 40mpg then although you're unlikely to achieve EITHER of those figures, you do at least know that car B will be less efficient than car A.
But my whole point is that this might not be the case for brisk drivers. Admittedly in an extreme example it is going to be, but as per my original post at 90 mph I get just over half the manufacturers claimed figure whereas I would bet there are many cars that are theoretically less efficient but which I will get better mpg at those speeds (quite a few have been mentioned above)RobM77 said:
Interesting. Well not 'interesting' as such but an eye opener.blindswelledrat said:
pherlopolus said:
S-type Diesel.
50mph - about 42mpg
60mph - about 42mpg
70mph - about 45mpg
80mph - about 42mpg
depending on traffic on my Telford to Bracknell trips its between 38 and 45 mpg on the OBC at the end
You get the same at 80 as 50? THat defies all known science. Are you sure?50mph - about 42mpg
60mph - about 42mpg
70mph - about 45mpg
80mph - about 42mpg
depending on traffic on my Telford to Bracknell trips its between 38 and 45 mpg on the OBC at the end
If you design a car from the outset to do 160mph then you have to make some design choices regarding aerodynamics, gearing, and engine sizing that will shift the economy sweet spot further up. A small engine working hard at high revs is less economical than a somewhat larger engine that's only just off idle.
In my experience:
N/A, MPG is the same whether pootling or hooning.
Turbo, MPG goes to pot the second you look at the happy pedal.
That and the eeevil of cancerous particulates mean PFI N/A is the only way to save the children.
The current cycle used for MPGs is the NEDC and I've tried to drive the cycle before and even in a super-eco-hatch you're using so little pedal movement that it's difficult (or I just have clumsy feet). The WLTP (which is supposed to be the new one coming soon maybe one day if they don't push it back again) is slightly better but still very Dorris.
I forget exactly but I think it involves more high load but it's high-load steady state so it'll benefit turbocancerwagons again at the expense of representative figures.
eta: suppose I should clarify a bit, I reckon transients are where you really burn fuel, i.e. acceleration rather than steady speed cruising. This is also where you make the worst pollutants, particularly particulates.
I seem to get 35MPG from a 2L n/a petrol no matter what I do with it. Not that I pay that much attention tbh.
N/A, MPG is the same whether pootling or hooning.
Turbo, MPG goes to pot the second you look at the happy pedal.
That and the eeevil of cancerous particulates mean PFI N/A is the only way to save the children.
The current cycle used for MPGs is the NEDC and I've tried to drive the cycle before and even in a super-eco-hatch you're using so little pedal movement that it's difficult (or I just have clumsy feet). The WLTP (which is supposed to be the new one coming soon maybe one day if they don't push it back again) is slightly better but still very Dorris.
I forget exactly but I think it involves more high load but it's high-load steady state so it'll benefit turbocancerwagons again at the expense of representative figures.
eta: suppose I should clarify a bit, I reckon transients are where you really burn fuel, i.e. acceleration rather than steady speed cruising. This is also where you make the worst pollutants, particularly particulates.
I seem to get 35MPG from a 2L n/a petrol no matter what I do with it. Not that I pay that much attention tbh.
Edited by scarble on Tuesday 3rd December 14:51
scarble said:
The current cycle used for MPGs is the NEDC and I've tried to drive the cycle before and even in a super-eco-hatch you're using so little pedal movement that it's difficult (or I just have clumsy feet). The WLTP (which is supposed to be the new one coming soon maybe one day if they don't push it back again) is slightly better but still very Dorris.
I forget exactly but I think it involves more high load but it's high-load steady state so it'll benefit turbocancerwagons again at the expense of representative figures.
Both are as pointless as each other if the loads are not wholly representative.I forget exactly but I think it involves more high load but it's high-load steady state so it'll benefit turbocancerwagons again at the expense of representative figures.
As I have said, the cycle is not the issue here. The test process prior to getting the vehicle on the dyno however...
Ohhh dont get me started on this one.....
The OH's little 1.0 Yaris (soon to be leaving the fleet, thank god) which has become the family/long distance car since my Lancia left the fleet returns 48mpg at around a steady 70mph but at around 80-85 the economy drops to around 38mpg and is hard work to maintain any speed consistantly.
Yet my modified 1242cc Cinquecento (poor mans toy) returns 46mpg at around 70mph yet only drops to 42 if i sit 80-85 and is mush easier to maintain speed with regards to having more power and torque to play with.
Sureely most of these mpg figures are a load of rubbish in the real world?
You would have thought these tests should be conducted at 70 mph this day and age?
The OH's little 1.0 Yaris (soon to be leaving the fleet, thank god) which has become the family/long distance car since my Lancia left the fleet returns 48mpg at around a steady 70mph but at around 80-85 the economy drops to around 38mpg and is hard work to maintain any speed consistantly.
Yet my modified 1242cc Cinquecento (poor mans toy) returns 46mpg at around 70mph yet only drops to 42 if i sit 80-85 and is mush easier to maintain speed with regards to having more power and torque to play with.
Sureely most of these mpg figures are a load of rubbish in the real world?
You would have thought these tests should be conducted at 70 mph this day and age?
Edited by rustyabarth on Tuesday 3rd December 15:01
For my commute, 60m round trip 75% busy motorway and the rest busy A roads, I alternate between a Peugeot 207 and a Mini One with the same 1.4 petrol engine. The best I can extract from the Peugeot is 47mpg and 52 from the Mini. The latter is lighter and has 6 speed box which would explain the difference. Rarely able to get above an indicated 70mph on the motorway due to traffic so in reality hovering around 65mph.
@rusty, is that a turbo Yaris? Or is it a case the teeny engine is really strained at that point
Like I say, I find n/as don't drop off much.
ks 
By "prior" you mean..? Stuff like the little cheats with tape, wing mirrors, tyre pressures or..?
Like I say, I find n/as don't drop off much.
zeppelin101 said:
Both are as pointless as each other if the loads are not wholly representative.
As I have said, the cycle is not the issue here. The test process prior to getting the vehicle on the dyno however...
Well more representative is better. You will never represent 100% of everyone's driving, there will always be a compromise. It's just that the current cycle is utter bAs I have said, the cycle is not the issue here. The test process prior to getting the vehicle on the dyno however...
ks By "prior" you mean..? Stuff like the little cheats with tape, wing mirrors, tyre pressures or..?
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