Best speed for fuel?

[Helga]

Hi, just done the sums, and
I'm getting about 22 to the gallon in my 82 2 litre Aircooled, but want to get it better, as that was without really trying - so what, do you think, would be the best cruising speed for fuel efficiency?

Cheers!!

[grumpyoldgit]

I get 26mpg in my 83 1900cc watercooled. This is averaged out over about 1200 miles in France this summer. On ordinary roads I do about 50mph max, often less. On motorways I try not to go over 60. This was 3 up with all our gear for a fortnight.
I am gentle on the accelerator and take my foot off well before junctions.

[VWCamperfan]

Agree with above post. 55mph is supposed to be a good speed to maintain a reasonable mpg return.

[HarryMann]

Constant energy driving, fast down-slope, letting it tail off on the climb (55 down, 55 up not efficient)
Always be aware of winds, don't keep pushing into or across winds, re-optimise speeds...
Read road well ahead, adjusting gear and speed accordingly, stay well back from car in front giving you room to drive at 'your' speed, and room to catch it up if you see no need to slow down prematurely when junction will clear or lights go green when you get there.
NB. Don't let economy driving threaten safe driving (speed for hazard, gear for speed, in that order)

Have now uploaded a blank Excel (2003) MPG spreadsheet to the Wiki archive, and can be downloaded and Saved from:

https://club8090.co.uk/wiki/Fu ... ownload.29

or here:

http://www.club80-90.co.uk/Downloads/MP ... _Blank.xls

It is easy to input your fills and will automatically plot the results, the chart can then be saved as jpg image at any time.

Please see the Wiki page (first url link) for basic usage details, PM me if any probs with usage.

Typical output:

[Rozzo]

i seem to remember in my dim and distant past reading an article about this. something to do with drag versus energy required to move through the air considering friction of tyres on the road and gravity etc. after all the technical mumbo jumbo the conclusion was that the optimum speed for economy was 56mph. this was for any vehicle.

[andisnewsyncro]

I think the assumptions that 56mph is the most fuel efficient speed simply comes from the old government fuel figure tables.
They used to quote fuel economy for "Urban" constant 56mph and a higher speed (which I've forgotten, was it 72mph ?) The best figure for any quoted vehicle was always the one at a constant 56, which it would be, rather than stop starting in the "urban" cycle or the sustained higher speeds. I don't think it's a blanket best speed for economy though. Individual vehicle's final gearing, tyre size, engine tuning etc must come into the equation somewhere.

As HarryMann says there are a lot of factors to take in and I've recently started watching my fuel a bit more closely. There's a lot of useful info on MPG in the Syncro section.
The spreadsheet is very handy for keeping track of your own vehicles performance

[Cruz]

I tend to get 17mpg urban

[matty o]

To be honest I try not to think about it,
It's a under powered 2ton brick and As long as you don't drive it like a gti you will nor make much diffrence
If it's a proplem it's time for a T4 oil burner.

[CovKid]

Best economy is braking as little as possible (too many brake last minute - use your gearbox to slow down too) and let the vehicle build up speed gently. Be in the right gear and DON'T carry onboard things you don't need all year round. You're paying otherwise. Motorways I can pootle at 60 but above that it will drink fuel. 6th gear would be nice at times! I can JUST do over 80mph in mine but wouldn't want to do it all day long.

[grumpyoldgit]

Best economy is braking as little as possible (too many brake last minute - use your gearbox to slow down too) and let the vehicle build up speed gently. Be in the right gear and DON'T carry onboard things you don't need all year round. You're paying otherwise. Motorways I can pootle at 60 but above that it will drink fuel. 6th gear would be nice at times! I can JUST do over 80mph in mine but wouldn't want to do it all day long.

6th gear!!! A 5th gear on mine would help. The only way it would ever do 80 is over the edge of a cliff.

[Cruz]

I've done 80 downhill on the M62 when not paying attention to the speedo

[Mocki]

just under 70 is the most economical for my 2.1 hitop, fully laden running on lpg on carb on motorways, went all the way down the m5 at 69mph got best mpg todate of 27mpg. But as has been said, stay off the middle pedle, and read the road well..... and never ever free wheel.

[weldore]

was just wondering...on a diesel(mines a 1y) does the same rule apply that when you are decelerating in gear does it use no fuel or is that just the petrol ones ?

[LUBO]

ZZZZZZZZ oops sorry. honest answer has been posted- these almost 2 ton bricks with never be eco bogey's. i also own an Aircooled(hightop camper). only way to live with it if you ain't loaded is only use them(campers that is) for what they where intended daily drivers on a budget they ain't

[HarryMann]

on a diesel(mines a 1y) does the same rule apply that when you are decelerating in gear does it use no fuel or is that just the petrol ones ?

Yes,the governor should cut the fuel to (almost) zero when on the overrun in a diesel