Freewheeling to save money

norsefox

Do it in any car that shows your current mileage and putting your car in neutral/foot down on the clutch CLEARLY saves petrol.

On holiday in France, by idling down the hill into the town in the valley, my Dad was able to max out the mileage (above 99mpg) in our VW Sharan.

Questions about safety aside, it will save money. Just as putting your foot down on the clutch and rolling into traffic lights does - marginal, but real.

OddballJamie

norsefox wrote: »

Do it in any car that shows your current mileage and putting your car in neutral/foot down on the clutch CLEARLY saves petrol.

On holiday in France, by idling down the hill into the town in the valley, my Dad was able to max out the mileage (above 99mpg) in our VW Sharan.

Questions about safety aside, it will save money. Just as putting your foot down on the clutch and rolling into traffic lights does - marginal, but real.

The fuel computer in my car shows a higher figure when I go down a hill in gear rather than when coasting.

Quick Update
Tested this on way home from work earlier. Clutch down went between 70-90MPG and increase in speed. In gear computer showed 999MPG car slowed slightly.

Ultrasonic

norsefox wrote: »

Do it in any car that shows your current mileage and putting your car in neutral/foot down on the clutch CLEARLY saves petrol.

On holiday in France, by idling down the hill into the town in the valley, my Dad was able to max out the mileage (above 99mpg) in our VW Sharan.

No simple 'test' that looks at instantaneous fuel consumption can prove whether coasting in neutral, or driving in gear with your foot off the accelerator is more fuel efficient (see my earlier post).

When going down hill you need to factor in whether any extra speed gained by coasting in neutral is useful (or safe, or legal). Down a steep hill coasting in gear can result in the ideal situation of using no fuel at all whilst maintaining a safe speed and not wearing out your brakes.

almillar

Yes OddballJamie - that's idling fuel consumption (freewheeling) vs zero fuel consumption (in gear, no pedals).
So the question in your example is: can I get down this hill at a decent speed in gear, or will it slow me down too much? If you're going to slow down, then have to accelerate, that zero burn is wasted, and you would have been better to freewheel for at least part of it.
I was reminded of another time that I freewheel a lot - in between speed bumps.