Which of these would return better mpg?

gaz_jones

Having an ongoing debate with a mate of mine.

WHich of these 2 scenarios would give you better mpg?


1) Driving in 4th gear and change up to fifth gear. fifth gear engages at 1500-2000 revs. The car doesn't have much pull in this rev range but it doesn't seem too unhappy to be driving at that lower rev range.

Or,

2) Driving in 4th gear and change up to fifth gear. Fifth gear engages at 2000-3000 revs. The car has pull from the second you put it into that gear.

Another way to put it would be:

1) Drive at 30 in 4th gear but engine wouldn't really pull the car if you had to put your foot down.

Or,

2) Driving in 3rd therefore having higher revs but car engine isn't struggling at all.


Both are the same question really just explained in a different way. Just incase my explanations aren't very good :rotfl:


Thanks everyone

anewman

Try both and compare. I think number 1. If you need to put your foot down then drop down a gear.

When I was taking lessons and about to do the test my instructor said it will be a minor fail point at some point in the future on a driving test to use too low a gear (termed something like economical driving).

Some cars have a green zone on the rev counter on the dash showing the range through which the engine is supposed to be most efficient - and this info is sometimes in the owners manual.

gaz_jones

I wouldnt be able to test it as i'd have to drive on a whole tank just like that.

I will have a look in the owners manual when i get back and see if they recommend a rev range.

Any other views welcome

Idiophreak

I've done plenty of tests over full tanks of short-shifting vs normal driving - if you change up around 2000 revs you will save fuel - but you will, obviously, accelerate a lot more slowly.

Lemonade_Pockets

It is completely dependant on the engine and car that you drive. Generally speaking i believe the advice for economical driving is you should always be in a gear that give you the lowest revs but where the engine will respond immediately. I.e. if you put your foot down the engine doesn't labour.

In my car a 2.0 diesel this is about 1900rpm. For normal driving i would say i drive between 1900 and 2200 rpm. This gives me the best economy all you have to stir the gear box a bit.