I have been thinking about this for some time now, but can’t really get the formula in my head. I have read almost all of the threads on ecomodder. I like t calculate measure design prototype redesign and build which is probably why i never get anything done

%10 gain is mentioned. Also 0.3l/100 km is mentioned. Which would be correct for a car that does ~3l/100 km.

If i had a diesel car that consumed 20l/100 km in the city and 10l/100 km on the highway would i expect to see 2l and 1 l gain respectively?

Or would it be 19.7l and 9.7l.

If we could somehow find a better formula it would be much more informative.

Such as if a car uses 350W and sees 0.3l gain. That makes 0.085l/100Wh (i assumed a steady speed of 100kmh). Or 0.85l/kWh.

If that were correct then it would be very easy to approximate the potential gains in fuel economy.

You want to run your blower motor at 100W. Sure thing, that will cost you 0.85 liters of gas in 10 hours. If this is the case (and I do run the blower motor a lot) it makes perfect sense for me to stockup a couple of kwh of batteries in to my car.

Modern cars also have lots of electrical gizmos from fuel pumps to sensors to actuators to power steering. Then it would also be easy to calculate the gain in a more electrified car. This formula would also permit me to understand what the gains would be in city fraffic.