I know we shouldn't put too much emphasis on manufacturers' performance figures (0-60. 60-0, mpg etc.,) when it comes to the real world.

But when these figures are obtained, how is the car set up? For example are they theoretical, is the mpg calculated on a test rig, does the car have a full tank of fuel, driver or 4 passengers, empty boot, spare wheel or what? A full tank of fuel is like carrying a passenger around with you

If manufacturers gave out figures for a fully loaded car, then that would be a worse case scenario and anything else (eg. no passengers) would be a bonus.