Car handling has been great in all gta games, gradually improving

.
GTA III and VC were VERY arcady and like the cars were glued to the road, but enjoyable to drive.
SA introduced some over and understeer in some occasions, car weight (could no longer push cars that easily by walking against them

) and nice wobbly suspension physics ( I loved the suspention in SA).
IV is another step up, making cars feel heavier, wobblier, and closer to what they're actually like. If you're flooring it and turning into a corner so hard that it's only barely keeping to the road, how can you expect it not to roll over to that side? You try getting into a big car perhaps a range rover or a Volvo V70 or so, and turn in as hard as you can @ high speed, the car is definitely going to tilt a lot... Cars in IV again have a bit more momentum, making blasting down the sidewalk running over hundreds of peds much more fun

.
The only thing I'm disappointed in in IV is the bike handling, feels too wobbly on the sports bikes, but that aside, imo car handling has been improving since every version since gta III.
I mean, go play vice city now, you can literally drive anywhere without ever releasing the throttle or using the normal brake, you just do handbrake turns everywhere while keeping it floored.