Car Fuel Consumption different depending on Journey direction?

Speed. Are the journey times identical?

Wind direction

Lay of the land - short/sharp gradients one way, long gradual gradients the other?

Traffic controls - maybe they are set to make getting out of London easier (less stopping and starting) than getting into London.

Fuel quality (if you fill up)

Load (luggage, fuel)

driver style (smooth & steady vs harsh stop/go)

Post additional details.

Rate of climb/descent can affect fuel consumption - not just the amount of climb/descent. As I recall, there's a pretty steep hill on the M11 just north of the M25, northbound - it's far more gradual southbound.

Also, how are you calculating fuel consumption? Filling up after each leg or believing the dashboard computer? If the latter, I suspect that it may only show the average fuel consumption for a certain distance and then start to 'discard' the older data - otherwise it'd have to store all measurements forever. Thus the last few miles of a journey probably affect the figures more than the first few. Try resetting the computer at , say, 10 mile intervals on each leg of the journey, noting the figures just before each reset.

Or use the 'refill' method to measure consumption.

For one thing the prevailing winds usually blow in the same direction so this may have an effect as the biggest contributor to fuel use, particularly once you go over 50mph is air drag. Air drag will be different for each direction of the journey.

Since there is little else that can be different if this occurs in all differing traffic conditions I reckon my theory will hold water there.

I am not an expert, but perhaps there is a slight incline going in one direction and slight downgrade going in the other..The wind working against you could also be a factor..How much of a difference in fuel are you experiencing? Happy driving, Jimmy

Next time you travel both ways, compare how many times you have to hit the gas. Whichever you hit more, and which ever you constantly have to hit harder to get more power, requires most energy. (Mostly shouldnbe because of a lot of stop signs, which means you will need boost power rather than just having a noce ride, or hills which your car needs more power.)

hundreds of different reasons!

- head wind one way, tail wind the other way

- one driver has a "heavier" foot than the other

- outside temperature

- maybe one of you uses the air-con while the other doesnt

- road surface may be different in each direction

- maybe one direction is virtually all uphill and hence the other is virtually all downhill

the list is endless!

The headwind on the way back

wind hills