Economy driving tip: drive faster!

[GainfulShrimp]

In case any other CR TDI Leon owners are thinking their mpg figures aren't as good as they should be, I've recently had a bit of a revelation... turns out I've been driving my Ecomotive far too gently.

My (admittedly basic) understanding of cars and mpg made me think that the gentler the braking/acceleration inputs, the better the mpg. But since the cold weather, I've been seeing worse figures than previously: about 58mpg tank average. It didn't improve much when the temperatures increased either.

So, after reading some tips on a hypermiling forum, over the last few days I've recently been using much more throttle to get up to speed: instead of accelerating as slowly as I could bear to and changing up as soon as recommended by the indicator, I've been using much more throttle (not flooring it, but very brisk acceleration) through the first few gears, then easing off as soon as I reach my desired cruising speed.
Because the low gears are inherently inefficient, it turns out that using more right foot to power through them quicker (and using more revs/boost in the process) is much more efficient than creeping the speed upwards and changing up asap to avoid using boost.

I've also increased my target speed/revs from about 52/~1,200 to about 62/~1,700. Driving *faster* by 10 mph in this way has actually improved my mpg too. Weird but true!

Seems counter-intuitive, but I'm certainly not complaining - just wanted to share this in case I'm not the only one who's been getting this wrong. Apparently it's something to do with the engine being more efficient between 1,500-2,000 revs than it is between 1,000-1,500 revs.

Once at cruising speed, I'm still using my tried and trusted techniques to maximise economy: trying to 'drive with load', avoiding cruise control, trying to anticipate ahead and avoid unnecessary acceleration/braking, etc.

I've been consistently seeing >65mpg journey average for my 40 mile commute since I started putting my foot down a bit more...

 

[Crafoo]

Just out of curiousity, how are you calculating the mpg? Are you using the onboard computer readout?

 

[Slimy]

I find my car runs at it's best mpg at 60mph, any higher or lower and the mpg drops. I don't remember what revs that is (it's about 3 something as it's petrol!), but it's pretty much where peak torque is. I burn as much fuel at 30 as I do at 90, both in fifth gear. I can get 30mpg out of doing 90, I get 40mpg from doing 60.

But that is with cruise control, I don't find much difference between my throttle control and the cars. Certainly going uphill it can drop to single figures, but down the other side it hits against the 200 limit on the indicator.

 

[Nath.]

Best MPG by a long way is 60MPH in my leon. I did 60 all the way to swindon and back (170miles) and got my best ever score of 52mpg.

 

[robdf2]

actually the most effeciet sweet spot for fuel economy is 56 mph so probably an indicated 60 mph on your needle

 

[gazR]

I find my car runs at it's best mpg at 60mph, any higher or lower and the mpg drops. I don't remember what revs that is (it's about 3 something as it's petrol!), but it's pretty much where peak torque is. I burn as much fuel at 30 as I do at 90, both in fifth gear. I can get 30mpg out of doing 90, I get 40mpg from doing 60.

But that is with cruise control, I don't find much difference between my throttle control and the cars. Certainly going uphill it can drop to single figures, but down the other side it hits against the 200 limit on the indicator.

you dont notice a difference? uses alot more fuel in my lcr which is why i only use it when i cant be bothered

 

[buzz w4]

I think best efficiency (mpg) comes at peak torque revs.

 

[Slimy]

you dont notice a difference? uses alot more fuel in my lcr which is why i only use it when i cant be bothered

I think perhaps when I'm controlling the gas pedal the tendency to accelerate a bit faster, then a bit faster, and then 'oh, if I go a bit faster I can get past the lorry before he does', then it's 'well, I'm already doing 80, so 85 won't matter', then it's 'right, time to show up this BMW muppet', and before you know it, I've arrived at work half an hour early, my fuel economy is in the toilet, and I can't get the paranoid image of flashing blue lights out of my rear view mirror....

At least if I switch the cc on all those decisions are made for me...apart from the BMW one...

 

[SpursMadDave]

In case any other CR TDI Leon owners are thinking their mpg figures aren't as good as they should be, I've recently had a bit of a revelation... turns out I've been driving my Ecomotive far too gently.

My (admittedly basic) understanding of cars and mpg made me think that the gentler the braking/acceleration inputs, the better the mpg. But since the cold weather, I've been seeing worse figures than previously: about 58mpg tank average. It didn't improve much when the temperatures increased either.

So, after reading some tips on a hypermiling forum, over the last few days I've recently been using much more throttle to get up to speed: instead of accelerating as slowly as I could bear to and changing up as soon as recommended by the indicator, I've been using much more throttle (not flooring it, but very brisk acceleration) through the first few gears, then easing off as soon as I reach my desired cruising speed.
Because the low gears are inherently inefficient, it turns out that using more right foot to power through them quicker (and using more revs/boost in the process) is much more efficient than creeping the speed upwards and changing up asap to avoid using boost.

I've also increased my target speed/revs from about 52/~1,200 to about 62/~1,700. Driving *faster* by 10 mph in this way has actually improved my mpg too. Weird but true!

Seems counter-intuitive, but I'm certainly not complaining - just wanted to share this in case I'm not the only one who's been getting this wrong. Apparently it's something to do with the engine being more efficient between 1,500-2,000 revs than it is between 1,000-1,500 revs.

Once at cruising speed, I'm still using my tried and trusted techniques to maximise economy: trying to 'drive with load', avoiding cruise control, trying to anticipate ahead and avoid unnecessary acceleration/braking, etc.

I've been consistently seeing >65mpg journey average for my 40 mile commute since I started putting my foot down a bit more...

Sounds like fun

 

[IRC Kevin]

Tried driving mine at various speeds from an indicated 60 to 65 mph a couple of months ago, but the mpg dropped by 3-7 mpg over my usual 56mph (indicated) consumption. My average had dropped somewhat since the weather got colder, but managed 65mpg (69 mpg best) on my run back from Windermere today - 40 miles M6, 31 miles mixed roads, with too many damn hills!

 

[/dev/null]

If you drive too slow in too high a gear then you will use more fuel as the engine has to work harder.

 

[bonehead2]

actually the most effeciet sweet spot for fuel economy is 56 mph so probably an indicated 60 mph on your needle

What makes you think 56mph is something special? It's different for all cars.

56mph is just 90km/h which is a common speed limit in Europe and as such is used for many economy figures as a standard, not because it has some special properties.

 

[GainfulShrimp]

Just out of curiousity, how are you calculating the mpg? Are you using the onboard computer readout?

For individual journey average mpg figures, I use the MFD readout as that's the only option really.

For long term average, I use an iPhone app called Road Trip which calculates stats about your fuel usage and costs. You just put in your odometer reading and fill up details (price, litres of fuel, location, etc) every time you fill up and it works out all sorts of stats for you. Very nice little app imho.

Interestingly, I've found that for my car the 2nd MFD mpg setting (which is a long-term average over the last X thousand miles) is near-as-dammit accurate. Certainly less than 0.5mpg different to what Road Trip calculates my average to be.

 

[chrisjgill]

For individual journey average mpg figures, I use the MFD readout as that's the only option really.

For long term average, I use an iPhone app called Road Trip which calculates stats about your fuel usage and costs. You just put in your odometer reading and fill up details (price, litres of fuel, location, etc) every time you fill up and it works out all sorts of stats for you. Very nice little app imho.

Interestingly, I've found that for my car the 2nd MFD mpg setting (which is a long-term average over the last X thousand miles) is near-as-dammit accurate. Certainly less than 0.5mpg different to what Road Trip calculates my average to be.

I use the same app and would agree. Noticed by making sure my tyres were at the correct psi and reaching desired speed quickly I am getting 52 mpg on individual runs. Overall in a week it's 48mpg. This is for a 80 mile round trip on 'A' roads where speeds reach 60 mph and occasional 30/40 sections.


Sent from my iPhone using Tapatalk

 

[asilaydying1234]

What makes you think 56mph is something special? It's different for all cars.

56mph is just 90km/h which is a common speed limit in Europe and as such is used for many economy figures as a standard, not because it has some special properties.

Ive also heard that 56mph is supposed to be the most economical speed for driving. It was in the papers and radio last year so im guessing that they must have carried out tests using a range of different cars and engine sizes and that 56mph is the average of all the various speeds where you get the highest economy!

Ive tried to explain nearly all of the above points to my dad who insists that driving at 30mph in 6th gear is the most economical and cause less engine damage... but as usual dads think they know best

 

[Crafoo]

For individual journey average mpg figures, I use the MFD readout as that's the only option really.

For long term average, I use an iPhone app called Road Trip which calculates stats about your fuel usage and costs. You just put in your odometer reading and fill up details (price, litres of fuel, location, etc) every time you fill up and it works out all sorts of stats for you. Very nice little app imho.

Interestingly, I've found that for my car the 2nd MFD mpg setting (which is a long-term average over the last X thousand miles) is near-as-dammit accurate. Certainly less than 0.5mpg different to what Road Trip calculates my average to be.

That's quite interesting, most people say that the trip computer isn't normally that accurate, but I guess if you have a consistent driving style then it's a lot easier for the trip to give an accurate reading.

 

[robdf2]

What makes you think 56mph is something special? It's different for all cars.

56mph is just 90km/h which is a common speed limit in Europe and as such is used for many economy figures as a standard, not because it has some special properties.

have a search on the net , i had that instilled in me since i was a nipper , thought it was common fact , oh well at least you learnt something

 

[IRC Kevin]

I do the same 71 mile journey every Friday night and back again on Sunday. The odometer on the Leon shows the same distance my S8 and A5 showed, and current Jeep is only 1 mile less for this journey, so I reckon it's a fairly accurate instrument. The satnavs have also given this distance. However, I think the fuel computer isn't accurate as it reads 10% more optimistically than actual fuel put in shows is being used. I always fill to just where I can see it (I know the extra weight is uneconomical, but what the Hell!) and use an Excel spreadsheet to work out fuel put for miles travelled.

 

[joolsvern]

I think perhaps when I'm controlling the gas pedal the tendency to accelerate a bit faster, then a bit faster, and then 'oh, if I go a bit faster I can get past the lorry before he does', then it's 'well, I'm already doing 80, so 85 won't matter', then it's 'right, time to show up this BMW muppet', and before you know it, I've arrived at work half an hour early, my fuel economy is in the toilet, and I can't get the paranoid image of flashing blue lights out of my rear view mirror....

At least if I switch the cc on all those decisions are made for me...apart from the BMW one...

pmsl, it was like you read my mind for that, fortunately I only hit the motorway once a week on average

 

[bonehead2]

have a search on the net , i had that instilled in me since i was a nipper , thought it was common fact , oh well at least you learnt something

Sorry, been away for a week or so and just catching up on stuff..

Anyway, who learnt something?? Me? I'm not trying to start an argument here, but it is true, the 56mph figure used is purely a standard set by the EU govt as a benchmark for fuel consumption averages so the manufacturers can print figures. Do you really think that all cars somehow miraculously reach their sweet spot at this speed???

So, accounting for drag coefficient, gearing, weight, etc, isn't it amazing that they all come out most efficient at 56...... Think about it..

The generally accepted "most efficient point" is the lowest speed your car can cruise at smoothly in top gear, whatever that may be.

As you said, have a look on the web, you might learn something...