I read your advice regarding the choice between an Audi A4 and a BMW 520d in Telegraph Motoring in August. I agree that the 520d is a heavier and bigger car than the A4 (just try sitting in the back seats). I took delivery of a 520d almost a year ago and was somewhat concerned about the performance and fuel economy having driven a 320d for most of the previous 3 years or so. The performance is actually very similar, but the economy of the new 5 is much better than the old 3. Over the long term, the trip computer showed 48mpg on the 320d and 57 mpg on the 520d; I also log the re-fuelling and miles and the calculated mpg on the 520d is not actually quite as good - over the last six months, it has generally been 52-55, never below 50. Obviously, this doesn't prove it's better than the SEAT Exeo or A4 - but it's a very respectable performance compared with these cars or even against many supposedly economical superminis.