# Does driving at 20mph in town take up more petrol than at 60mph on the motorway?

deleted44407
Posted 10th Mar 2012
Is this true?

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1. Driving at a costant 20mph will use less fuel than 60 on a motorway. The reason town driving uses more fuel is due to the inconsistent speeds, the constant stop start, pulling away and going up through the gears.
2. The OP:

3. 80-95mph is what I find works out the best
4. Orcinus_orca

Does driving at 20mph in town take up more petrol than at 60mph on the … Does driving at 20mph in town take up more petrol than at 60mph on the motorway?

Toasthduk

No, For one bicycles do not use petrol and second you can not ride your … No, For one bicycles do not use petrol and second you can not ride your bike on the motorway

fanpages

...and you do not drive a bicycle.

Toasthduk

Yawn

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5. Depends.
6. Well it depends if you are trying to get away with a stolen phone or not.......
7. whatsThePoint

at a constant 100 mph my bike does more to the gallon than it does at a … at a constant 100 mph my bike does more to the gallon than it does at a constant 140mph

Wow you must peddle really really fast!
8. whatsThePoint

forgot to say thats peddling up hill speeds

Into the wind, yea?
9. In my experience, 60-70 on the motorway is more economical than any form of town driving.
10. ncolli

Driving at a costant 20mph will use less fuel than 60 on a motorway

Driving for the same amount of time, yes. But I'm assuming the OP wants to know which is more economical with regards to mpg.

50mph is widely recognised as the most economical speed; stands to reason you'll be closer to this magic figure at 60mph than you will at 20mph.
11. ncolli

Driving at a costant 20mph will use less fuel than 60 on a motorway. The … Driving at a costant 20mph will use less fuel than 60 on a motorway. The reason town driving uses more fuel is due to the inconsistent speeds, the constant stop start, pulling away and going up through the gears.

I'm ready to be corrected and interested in the answer, but I don't think that is necessarily true, although the part about inconsistent speeds is.

My very limited understanding of the mechanics is that an engine will use a minimum amount of power to get to x miles per hour, hence the historical 57mph 'ideal' economic cruising speed.

So, even if it is just turning over it uses a certain amount of fuel and although this will be affected by gears and speeds, and you may well be correct on the 20 vs 60 mph example, I don't think the "low speed always economically outperforms higher speed given a level playing field" idea is necessarily true.

But I'm always happy to be educated...
12. ncolli

Driving at a costant 20mph will use less fuel than 60 on a motorway. The … Driving at a costant 20mph will use less fuel than 60 on a motorway. The reason town driving uses more fuel is due to the inconsistent speeds, the constant stop start, pulling away and going up through the gears.

That's a rash statement and utter crap.
It depends upon the revs the engine is doing and the efficiency of that engine. Try doing 20mph in either 4th 5 th or 6th gear if you have one. It ain't gonna happen so for any car regardless, running the engine at the same revs in the highest gear may well produce 60mph and will use less fuel than driving at 20.
13. pretty obvious that driving at a constant 20mph will use less fuel than driving at a constant 60mph.

Obviously, you'll only cover 1/3rd of the distance in the same amount of time!
14. at low speeds you use lower gears which are in fact heavy gears ...n can use more petrol... then driving a constant speen on motorway on high gear... practically you might realize when pressing the pedal... you would probably press same amount in either case of speeds
15. Why don't you go for a drive in town, then go drive on a motorway and then you will get your answer
16. No, For one bicycles do not use petrol and second you can not ride your bike on the motorway
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17. Orcinus_orca

Does driving at 20mph in town take up more petrol than at 60mph on the … Does driving at 20mph in town take up more petrol than at 60mph on the motorway?

Toasthduk

No, For one bicycles do not use petrol and second you can not ride your … No, For one bicycles do not use petrol and second you can not ride your bike on the motorway

...and you do not drive a bicycle.
18. Orcinus_orca

Does driving at 20mph in town take up more petrol than at 60mph on the … Does driving at 20mph in town take up more petrol than at 60mph on the motorway?

Toasthduk

No, For one bicycles do not use petrol and second you can not ride your … No, For one bicycles do not use petrol and second you can not ride your bike on the motorway

Yawn
19. Subscribed!! X)
20. csiman

pretty obvious that driving at a constant 20mph will use less fuel than … pretty obvious that driving at a constant 20mph will use less fuel than driving at a constant 60mph. Obviously, you'll only cover 1/3rd of the distance in the same amount of time!

Hows it obvious? As stated above the most economical speed for a car is supposed to be around 57Mph.

[image missing]

Hows it obvious? As stated above the most economical speed for a car is … Hows it obvious? As stated above the most economical speed for a car is supposed to be around 57Mph.

thats MPG, not fuel used over the same time period.
22. csiman

thats MPG, not fuel used over the same time period.

OK poor example however, cars use more fuel in lower gears.
23. Author
Teeth_Extractor

Subscribed!! X)

you are banned from posting in my threads (my rule)
24. I get 34mpg at a constant 60mph ( i have a zafira gsi 2.0 turbo )get around 430mile out of the tank motorway driving

town driving it can be 18mpg- 32mpg just depends on traffic etc i get 320miles from the tank
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25. YES.
26. Does it even matter to you OP? I mean... you don't pay for your petrol do you?