Hi Gizze - I've read your posts on this as I was curious to know why you were no better off with a diesel than a petrol and you say the difference between an E350 and an E320cdi was 5mpg - I'm not doubting this, but I think this is an exception rather than "the norm"
When I changed cars earlier this year after changing jobs and going from doing about 4000 a year to doing about 25000 a year.
assuming of my 25,000 miles that 20,000 is motorway my new car regularly does 54 to the gallon which would cost me £2054 at todays pump price - the best I could get from the 325i was about 32mpg - which would cost £3402 at todays pump price - so the c class saves me £1400 a year in fuel costs - over £100 a month.
now agreed i had to buy a new car - but I was going to do that anyway - also agreed the latest 325i is probably more efficient than my last one and i know from looking around that i'd have paid about the same for a 325i and the c200cdi I bought, all things (age, mileage, condition etc) being equal - actually the 325 woukld possibly have been a bit more. but still - the c220 i have now is only 15bhp down on my old 325 and has a lot more torque, it isn't as refined but is easier to cover ground in as it's quieter and an auto box - for me the diesel thing is a no-brainer really. and as I said in my last comment - i wondered if they still made petrol 'c' and 'e' class cars as everyone buys diesels (same could be said for 3-series and 5-series bms of course) - cos the diesels are so good these days!
But you are comparing a 4 pot diesel with a BMW straight six petrol, and a previous generation.
As the cars get heavier you have to start moving their own weight, and this is the killer for fuel consumption, which is also why the rolling road tests for mpg are worthless.
If you had bought a 320d you would be getting 60+ all day long, I often saw 70 mpg from our efficient dynamics model.
However, our 535d would not get above 36mpg, often at 22mpg and averaged 26 over the 25k miles and 10 months I had it. The same car with the new ZF 'box returned over 30% better economy, everything else was the same.
My old C220cdi estate, 2001, was an auto and used to average 36mpg, my E46 320d touring was an auto and averaged 32mpg, a lot changes in 5 years with cars.
If you want the economy from a diesel then go for the smallest car you can and stick with a 4 pot, auto or manual makes sod all difference with the very latest 'boxes, well from BMW they tend to be slightly better.
By the way, the new 325i/330i will return 30-40 mpg no problem, the 330d returns 38-48 no problem, so there is a difference, just that I think most people think the petrols are only going to get 18-28mpg, but things have moved on.
