Quote from wheel4hummer :

Just adjust the fuel and look at how much the total mass of the vehicle changes. Simple.

EXACTLY. very simple,and quick(unless you are a failing person)

Quote from amp88 :

The variance in temperature wasn't to do with the ambient temperature. The clever teams used to bring refrigerators to the track so they could cool the fuel down well below the ambient. I'm sure I have a video somewhere showing -20 or -30 degrees Celsius on a Renault fuel refrigerator from the 1980s. Once the fuel actually goes in the car it's very close to the engine so it quickly heats up above the ambient, but of course some has been burnt already so the increase in volume doesn't cause over pressuring in the tank.

I was just watching the 2002 Bathurst race from the V8 Supercars championship and there was an incident which reminded me of this topic. Peter Brock's car was having problems with overheating, so they brought it into the pits to try and fix it. As a matter of course they filled the car full of fuel (from a reservoir which held the fuel at ambient temperature, not a chilled reservoir!) and changed the tyres. The car sat in the pits for a few minutes with the engine turned off while the mechanics and engineers attempted to source the problem. After a few minutes the car actually started spilling fuel because the fuel had increased in volume as it sat in the tank being heated by various parts of the warm car. In V8 Supercars the fuel tank is at the back of the car (and the engine is at the front), but although the engine is far away from the fuel tank there are other heat sources in the vicinity (rear brakes, diff, oil tank etc) which heated the fuel, causing it to expand in volume and overflow the tank, creating a fuel spill in pitlane. Anyone who doubted the effect of temperature on the volume of fuel needs only to think of this example.