@Clive / John
I'm enjoying the banter hence the thumbs up icon :).
@Clive and John
I know for a fact that my onboard computer figures are very inaccurate. If I believed my onboard computer I'd be driving a car made by Jesus as it currently claims I'm getting 70.4 mpg. It's not too clever unfortunately. However I'm quite an anal person and regularly (almost always) reset my trip each time I fill up my tank.
@Clive
The 47mpg you saw looks like the Urban figure (i.e. in town). You're clearly doing longer runs than just running round town if you've done 50,000 miles in the Prius. The BMW UK site states 47mpg Urban, 68.9mpg Extra-Urban, 58.9mpg Combined. I generally do a 40 mile commute on a good stretch of road and leave cruise control on, hence my 60mpg isn't unrealistic.
This tank I have currently driven 530 miles and looking at the guage have used around 40 litres. This equates to 60.3 mpg (imperial). Previous figures have varied from 48 to 61mpg depending on how I drive it.
Some other figures... (320d | Prius)
0-60mph: 7.9s | 9.8s
HP: 177 | 76
CO2: 128 | 120
Combined MPG (Official figures): 58.9 | 55.4-65.6 depending on where you look.
The CO2 and MPG are pretty close.