If you're struggling to get your car to produce the same fuel economy as the maker's claim then you're not alone.
We routinely hear from compact car owners aiming for 8 litres/100km but only making around 12 in the city, as well as drivers of family-sized SUVs who are struggling to better 15 litres/100km on their stop-start city commute.
Yet you can take a Holden Commodore SS ute, drive it gently on the freeway using high gears and light throttle in the meat of the torque band, to return extraordinary sub-10 litres/100km numbers.
The biggest problem for economy-conscious drivers is the way the official economy numbers are generated, using a static test of a car running on a "rolling road" to a pre-set drive route. There is no wind drag, no real hills, no baggage and — surprise, surprise — carmakers use special drivers who score best during coaching on the "test" run.
But there is finally a move to real-world economy testing in Europe and the PSA group from France — makers of Peugeot, Citroen and DS cars — is out first with some shocking results from tests certified by the independent Transport & Environment and France Nature Environment organisations.
It must only be a matter of time before the whole world switches to the new French system.
In truth, there is no shock at all because the numbers were produced on 100km of public roads, driving cars with people and baggage on board, and even running the aircon.
Only four of the PSA test cars line up with the ones sold here, but their results show a thirst that's at least 30 per cent higher than the official economy results in Australia, with the others well into the 40 per cent range.
So now you know and it must only be a matter of time before the whole world switches to the new French system.
Existing economy numbers allow showroom comparisons between rival cars, but they are ridiculously better than owners can expect in the real world.
Were you surprised with the "real world" fuel consumption of your car? Tell us what you think in the comments below.