Working out MPG on a D24

[clivealive44]

I used to have a 245 D24 with M47 with overdrive, i used to get about 29/30 mpg city driving, but the mpg stayed about the same country driving aswell. The gearbox was very reliable. As far as i can remember the m45 is the 4 speed, the m46 is the 5 speed and the m47 is 4 speed with overdrive. I was told the m45, and m47 were much stronger boxes than the m46. (don't know if it's true or not)