MPG imrpovement tips
Discussion
Right, PH massive.... I have a question/need a solution (if there is one):
The OH runs my 1.9TID SAAB 9-3 for 300-450miles a week, mainly motorway, and over the last 1600+ miles, has averaged a fairly healthy 46.7MPG (COMBINED) which I thought was pretty damned good.
Question is, what basic stuff can I do to the car or get her to do when driving to increase it's MPG further?
Daily journey is: Morning -22miles of constant motorway, and 4miles each end of town driving. Then the reverse at night.
Car runs 150bhp as standard, and 225/45/17 tyres.
I've suggested injector cleaner, learn to drive less throttle happy around town, and plan routes to avoid stop/start traffic. Also, all crap that ain't needed has been ditched from the car.
Any more suggestions?
The OH runs my 1.9TID SAAB 9-3 for 300-450miles a week, mainly motorway, and over the last 1600+ miles, has averaged a fairly healthy 46.7MPG (COMBINED) which I thought was pretty damned good.
Question is, what basic stuff can I do to the car or get her to do when driving to increase it's MPG further?
Daily journey is: Morning -22miles of constant motorway, and 4miles each end of town driving. Then the reverse at night.
Car runs 150bhp as standard, and 225/45/17 tyres.
I've suggested injector cleaner, learn to drive less throttle happy around town, and plan routes to avoid stop/start traffic. Also, all crap that ain't needed has been ditched from the car.
Any more suggestions?
Ensure tyre pressures are correct
remove un-necessary weight
avoid using the brakes, instead decelerate by lifting off the throttle or using 5th gear if it's a 6-speed. braking on the motorway = failure and you must slap yourself if you do it. It means you're folowing too close.
ETA: don't bother with injector cleaner IMO. It ain't what it used to be and you'd certainly know about it if you had a clogged nozzle.
remove un-necessary weight
avoid using the brakes, instead decelerate by lifting off the throttle or using 5th gear if it's a 6-speed. braking on the motorway = failure and you must slap yourself if you do it. It means you're folowing too close.
ETA: don't bother with injector cleaner IMO. It ain't what it used to be and you'd certainly know about it if you had a clogged nozzle.
6speeder. Told her to slow in gear as IIRC they run on next to zero fuel, momentum keeps engine spinning.... Or is that b
ks?
In terms of interior weight... There's a high vis coat, her handbag.
Only extra stuff in boot: Space saver wheel and tool kit.
Would it be worth only 1/2 filling the car each week, instead of brimming it every 14days, thus running 1/2 tank, less weight?
ks?In terms of interior weight... There's a high vis coat, her handbag.
Only extra stuff in boot: Space saver wheel and tool kit.
Would it be worth only 1/2 filling the car each week, instead of brimming it every 14days, thus running 1/2 tank, less weight?
NotDave said:
6speeder. Told her to slow in gear as IIRC they run on next to zero fuel, momentum keeps engine spinning.... Or is that bks?
Pretty much true, if the clutch is engaged (i.e. the pedal isn't down) and you aren't touching the throttle it is using very little fuel at motorway speeds.ks?NotDave said:
Would it be worth only 1/2 filling the car each week, instead of brimming it every 14days, thus running 1/2 tank, less weight?
Well, (assuming a 55l tank) half-filling it would be a ~24kg saving in weight, but the difference in economy would be so miniscule that you'd probably waste it just visiting the filling station twice as often... Dont worry about the fuel, IME having a full tank makes no difference.
ETA: Forgot this one - turn off aircon (ECON mode) if not needed, this does make a difference.
- Make sure the oil is at the correct level and that it is serviced on time.
- Make sure the tyres are at the correct pressure.
- Keep speed on the motorway down to the legal limit
- Whenever possible coast down in gear when slowing , this will use zero fuel as the injectors cut off.
- When following in traffic keep a good distance from the vehicle in front so you can avoid braking
- Look well ahead and plan speed accordingly e.g. if you see red lights slow down a bit to try and continue through when they go green. Same with roundabouts - try to carry speed through the roundabout
- Momentum is everything, lose it and you have to use fuel to get it back.
ETA: Forgot this one - turn off aircon (ECON mode) if not needed, this does make a difference.
Classic Grad 98 said:
NotDave said:
6speeder. Told her to slow in gear as IIRC they run on next to zero fuel, momentum keeps engine spinning.... Or is that bks?
Pretty much true, if the clutch is engaged (i.e. the pedal isn't down) and you aren't touching the throttle it is using very little fuel at motorway speeds.ks?The fact that you're not just saving fuel, you're literally using none at all, is great incentive to look ahead, predict what will happen, and act early enough to ease off and use engine braking rather than leaving it late, burning more fuel on your way there, and then using the brakes.
This sort of mindset is the way you will save fuel. Always looking ahead and predicting what speed you'll need to do, etc, means you can make gradual adjustments and hardly ever get caught out and have to brake. Braking should be considered a pure waste of fuel - because if you're braking, you could have eased off earlier and burnt less.
Also worth mentioning that power required increases with the cube of speed.
http://www.hypermiler.co.uk/tag/hgv-drafting
Although I really haven't had the nerve to do it. Even at a 2 second gap the fact I can't see round it make me nervous.
Although I really haven't had the nerve to do it. Even at a 2 second gap the fact I can't see round it make me nervous.
doogz said:
When you consider the rotational inertia of the crankshaft itself, and flywheel, and clutch, then consider that of the input shaft and rest of the clutch, i doubt you'd ever notice the difference in fuel consumption.
Could be wrong. But i doubt it.
I agree. The inertia of the input shaft (deliberately minimal) and the clutch are as nothing compared to the flywheel, pistons, conrods (often overlooked but very significant) and the crank. For longevity, maybe it'd be better to use neutral for long stops, but for fuel it won't do anything noticeable.Could be wrong. But i doubt it.
I would even venture that the fuel burnt in the half-second longer you need at idle to re-engage first will be far more than you saved by reducing idle inertia
A2Z said:
http://www.hypermiler.co.uk/tag/hgv-drafting
Although I really haven't had the nerve to do it. Even at a 2 second gap the fact I can't see round it make me nervous.
I have done that when following my dad who was towing a box trailer. It makes a massive difference. It's like when racing you use another competitors slipstream, it feels like the car in front is 'sucking' your car closer. If you want to maintain the gap you have to literally reduce your throttle opening.Although I really haven't had the nerve to do it. Even at a 2 second gap the fact I can't see round it make me nervous.
Classic Grad 98 said:
Ensure tyre pressures are correct
remove un-necessary weight
avoid using the brakes, instead decelerate by lifting off the throttle or using 5th gear if it's a 6-speed. braking on the motorway = failure and you must slap yourself if you do it. It means you're folowing too close.
ETA: don't bother with injector cleaner IMO. It ain't what it used to be and you'd certainly know about it if you had a clogged nozzle.
Braking means you wasted fuel not while braking, but beforehand while accelerating or maintaining a higher speed than you need. Doesn't matter if its wheel brakes or engine braking.remove un-necessary weight
avoid using the brakes, instead decelerate by lifting off the throttle or using 5th gear if it's a 6-speed. braking on the motorway = failure and you must slap yourself if you do it. It means you're folowing too close.
ETA: don't bother with injector cleaner IMO. It ain't what it used to be and you'd certainly know about it if you had a clogged nozzle.
In other words, if you're downshifting to get the required rate of deceleration, it's no better than getting the same deceleration rate with the wheel brakes.
So the goal is to need to slow down less often and to scrub off less speed while doing so. Of course, actively trying to avoid using the brakes does help because it makes you think about what's likely to happen up ahead, and keep bigger following distances, and so on. But avoiding having to downshift to get more engine braking helps too.
My big tip to the OP: Knock 5mph off her typical motorway cruising speed. If she usually drives at 70ish, then drive at around 65ish. When she comes across someone doing 63, then travel at 63 instead of speeding up to overtake (or plan carefully to avoid needing too much throttle to get past - e.g. go past on a downhill). It feels funny for a while (as in it's going to be difficult for a couple of days) but that's only because your ear gets used to the engine revs needed for the current pace and your eyes and brain get used to taking in information at the current speed. At first it feels boring and unnatural and perhaps even uncomfortable to the point that it almost feels dangerous, but the mind acclimatises soon enough, so don't just try it for 5 minutes and give it up as a bad joke.
I hear that turning cruise control off helps too. Not sure if its true.
Edited by Alfanatic on Wednesday 1st February 11:31
Thanks folks, been some helpful suggestions.
As for slip-streaming, think we'll keep her off that one... For now. I know from personal experience it works. 1400cc rover, London to N Lincs, following a mate in his stilo. lepton, 40mpg all the way
As for the clutch down bit, I've told her before, shall explain tonight again. AFAIK it's using next to zero fuel, and better than neutral as neutral will cause the car to idle. Where as slowing down in gear will help.
Tyre pressures/wear...... Oil...... Water..... Servicing: All of this is done, BY ME, far far more often than SAAB reccommend. On advice of local mechanic who's worked on my cars and my dads for 20 years. I chuck redex or such like in it once a month too.
4 questions:
1) the full tank VS half tank.... It's around a 70 litre tank IIRC. So 1/2 is 35litres. 35KG of weight..... not make a difference?
2) Exhaust systems on diesels, i.e. DPF and CAT.... Is it still true that dervs need a good bit of abuse to clear them out on a weekly/monthly basis? I.e. up a 4mile long DC uphil, 2nd/3rd/4th on full bore, to the rev limiter? been told that it keeps things clean and clear
3) remap - are they worth it? 180bhp and better torque figures as well as better MPG, the outlay worth it? She's going to be running this mileage and car setup of mine for 12months at least
4) CRUISE CONTROL - on or off? I always thought "ON" made it better, but colleague at work argues other wise. She likes using it, and feels safer cruising not up speed down speed cycling
As for slip-streaming, think we'll keep her off that one... For now. I know from personal experience it works. 1400cc rover, London to N Lincs, following a mate in his stilo. lepton, 40mpg all the way
As for the clutch down bit, I've told her before, shall explain tonight again. AFAIK it's using next to zero fuel, and better than neutral as neutral will cause the car to idle. Where as slowing down in gear will help.
Tyre pressures/wear...... Oil...... Water..... Servicing: All of this is done, BY ME, far far more often than SAAB reccommend. On advice of local mechanic who's worked on my cars and my dads for 20 years. I chuck redex or such like in it once a month too.
4 questions:
1) the full tank VS half tank.... It's around a 70 litre tank IIRC. So 1/2 is 35litres. 35KG of weight..... not make a difference?
2) Exhaust systems on diesels, i.e. DPF and CAT.... Is it still true that dervs need a good bit of abuse to clear them out on a weekly/monthly basis? I.e. up a 4mile long DC uphil, 2nd/3rd/4th on full bore, to the rev limiter? been told that it keeps things clean and clear
3) remap - are they worth it? 180bhp and better torque figures as well as better MPG, the outlay worth it? She's going to be running this mileage and car setup of mine for 12months at least
4) CRUISE CONTROL - on or off? I always thought "ON" made it better, but colleague at work argues other wise. She likes using it, and feels safer cruising not up speed down speed cycling
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