It depends on what you understand to be handling. I used to own a 330i Sport and coincidentally I came across a 330i on the motorway recently, he was confident that he would be quicker... but he wasn't. He tried all the way up to 140mph but the 4.8is (with four people on board) would just pull away at any speed. Anyway I digress, that's nothing to do with handling.

Ultimately around a circuit or twisty road course the 330i would be quicker, mainly due to it's ligher weight, lower intertia, lower CofG and greater agility. If the turns were less acute then the difference would be far less. Lateral grip would be very similar and perhaps in the 4.8is favour since in grips like a demon. Unlike any other SUV I've driven I can put the 4.8is into a four wheel drift which means requires exemplary body control for something with such a relatively high CofG. Where the 4.8is loses out is through a sequence of Left/Right turns where the momentum builds and the suspension cannot contain the masses as neatly as would be the case in the 330i.

Personally my definintion of good handling has to include a number of factors; steering feel and accuracy, body control and agility, the ability to flow between corners in a balanced manner, being able to feel the sweet spot (the car's centre of mass) through the seat of your pants and ultimately does it put a smile on your face and make you want to go back and tackle a challenging road again. I found my 330i very effective (i.e. quick) but not as much 'fun' as I find my 4.8is. The steering on the 4.8is is better IMO and there is greater reward in getting a corner right, but the 330i is an all-round near perfect saloon/sedan so it's hard to compare objectively.

The overriding feeling I have when driving the 4.8is is "why aren't the mainstream BMW saloons even better?" Clearly a lot of clever engineering went into creating such an agile, sporty big car and it means that whenever I go and drive a 645Ci or 330i today, I find myself dissappointed that they don't blow my socks off. To put it in perspective I also have an M3 CSL in my garage and it's an amazing car, but I drive my 4.8is more often and don't find myself wishing I was in the CSL very often.

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