Q&A for How to Hypermile

If it's a manual transmission (stick shift), then you're either not using the clutch or you're not pushing the clutch all the way down. If it's an automatic transmission, it's not you that's changing gears. So, take it to a mechanic.

Using the heater does affect gas consumption because running the fan takes about 50 watts electrical from the engine. But because the thermal losses from the engine are so significant the 3 KW thermal that your heater puts out is free, so in this respect the heater does not increase fuel consumption.

Dry air will remove fog from your window. So, use the air con, that's one of the reasons it's there.

No. The internal resistance of the car battery is too low, the battery will heat up slightly because there is current flowing through the cells, but almost all the energy will go into heating up the light bulbs principally, then some into heating up the wires, and lastly a little bit to heating up the battery. In the situation of winter starts, you will want all the energy you can get to turn the engine so minimizing losses to auxiliary loads is important.

To be specific, diesel is more dense than petrol. Diesel being roughly .85 kg/litre and petrol being .75 kg/litre. Interestingly enough, they both contain roughly the same amount of energy per unit mass but most often you purchase fuels by volume so this doesn’t concern us often.