Questions on fuel consumption.

10th February 2011, 13:21

my car is vtr, decatted.

If i am travelling as say 50 for example, and im going down a steady slope, am i right in thinking if i put it in neutral is will save petrol?

if the car is at 30mph, if i put it in 5th will that save petrol?

Whats the best rev 'number' to change at to save fuel?

dont go above 2000?

10th February 2011, 14:02

If you go down a slope in neutral, you will gain speed. So what petrol you save will go into buying new brake pads!

Keeping it in 5th, then the gear will hold the car back, and taking your foot off the throttle, is probably most economical. It will use next to no fuel like this. Putting it in neutral uses just as much fuel IMO.

2000rpm is a little low to be changing gear, because you will have to accelerate more in the next gear to be making decent progress. I'd change up about 2500rpm.

30mph is fifth is only any good on flat or sloping land. Going uphill in 5th at 30mph will labour the engine, drinking more fuel.

10th February 2011, 14:06

The Eco Bible. Next time use the search button or look at the stickies

10th February 2011, 14:23

yeah ill use the search button haah cba before

thanks.

10th February 2011, 15:18

Quote:

Originally Posted by Meto

If you go down a slope in neutral, you will gain speed. So what petrol you save will go into buying new brake pads!

Couldn't have put it better lol!

Yeah the VTR Ecu will halt the flow of fuel into the engine when it detects a closed throttle at anything above idle speed. So you're best to stay in gear and let your foot off the accelerator, by putting it into neutral means fuel is used to maintain idle but it's not actually being used to apply motion to the car.

Ads

10th February 2011, 15:24

Cars use a iny bit of fuel in neutral to stop themselves from stalling, but its a tiny amount, just dip the clutch to the floor and keep it in gear. as revs go i change at around 2200 and it seems to be really economical, and i cruise around at about 1500-1800, dont go in too high of a gear as it will make the engine struggle to keep the revs and waste just as much as flooring it.

10th February 2011, 15:45

Quote:

Originally Posted by Karlb1

Cars use a iny bit of fuel in neutral to stop themselves from stalling, but its a tiny amount, just dip the clutch to the floor and keep it in gear. as revs go i change at around 2200 and it seems to be really economical, and i cruise around at about 1500-1800, dont go in too high of a gear as it will make the engine struggle to keep the revs and waste just as much as flooring it.

Wrong! Cars actually run slightly on the rich side to stop people stalling as they pull off from a standstill, whereas in gear and off the accelerator your car will cut the fuel using virtually no fuel at all. Coasting is not good for fuel consumption.

10th February 2011, 16:45

Quote:

Originally Posted by KamRacing

Wrong! Cars actually run slightly on the rich side to stop people stalling as they pull off from a standstill, whereas in gear and off the accelerator your car will cut the fuel using virtually no fuel at all. Coasting is not good for fuel consumption.

i agree

and isnt coasting illegal anyway because you dont have full control of the vehicle.

10th February 2011, 19:34

Quote:

Originally Posted by Gazer

i agree

and isnt coasting illegal anyway because you dont have full control of the vehicle.

asif the po po are going to catch you though

10th February 2011, 19:44

Quote:

Originally Posted by VTHall

asif the po po are going to catch you though

I'll grass ya up

16th February 2011, 10:49

Quote:

Originally Posted by Gazer

I'll grass ya up

haha, prove it

16th February 2011, 14:35

neutral will save fuel . i know i do it all the time when going to a certain place --i go up the hill ,then at 60mph,that i have found is speed rquired to end up at 30mph at other end in the village i put it in neutral and i can coast all the way to the pub some 3 miles down the hill,gets bit hairy on corners ,as i don,t want use the bakes--but yes technically it will save fuel--but a very small .
my car has an instant mpg gauge ,so on lift off down the e hill it would show less mpg anf if i free wheeled --
rover + saab used to make cars with a free wheeling dif on them --very scary first time you drove one ,as it seemed to accelerate to the corners as you lifted off at the normal distance you would in a normal car--so ou just lift off sooner .
--all good fun

16th February 2011, 18:00

Quote:

Originally Posted by VTHall

haha, prove it

dont worry i got video evidence

17th February 2011, 09:23

I tend to keep it at 3000! before changing gear

but thats my car! arnt they all a little bit different!