The thirstiest Rover car ever built must be the original JET 1 gas turbine car, without regenerative heat exchangers, which could consume kerosene at the rate of 1 or 2mpg! The final T4 turbine car could achieve between 10 and 20mpg.Cool photos of Jet 1 here and here. I could see myself driving one of these. I had a look at this car in the British Science Museum about 20 years ago. I love this sort of styling.