E92 325i and 330i question

[MitchT]

Just browsing a couple of coupés... Both of these cars have a 3.0 engine and similar fuel consumption, but the 330i has better performance than the 325i. What factor is different between the two to achieve this and what is the point of the 325i if the 330i delivers better performance without, seemingly, burning any more petrol?

[RiccardoG]

We have a 325i (E91, Touring) in the family, the only reason its a 325i is that it was substantially cheaper than a 330i as we purchased it new and with our own spec.

As a used buy I would certainly prefer the 330i. The 325i is not quick at all, despite its 220 or so bhp. Personally I also think that an automatic gearbox is better for this engine as the manual gearbox is relatively long throw and very 'rubbery' in its engagement.

[MitchT]

It certainly seems to make sense to go for the 330i used as they don't seem to cost any more than 325s of comparable age and mileage.

Does anyone know the answer to my original question? In what way does the 325i differ from the 330i - They both have a 3.0 engine but the 330i has more power? How is it that two identical engines produce different amounts of power?

[RiccardoG]

MitchT said:

Does anyone know the answer to my original question? In what way does the 325i differ from the 330i - They both have a 3.0 engine but the 330i has more power? How is it that two identical engines produce different amounts of power?

I looked into this as well as I wanted to know if there would be a way of upgrading our 325 to the performance of a 330. A post on the E90 board didn't yield many answers, though the general opinion was that there would have been the need for a new ECU, exhaust manifolds and something else, all of which added up to a considerable expense. Also, IIRC, the 25 has a different autobox from the 30 (GM vs ZF). None of this is fact though, so please let us know in case you find out something different.