I learnt from the Project Cerbera school of handling setups, and have made my own series of tweaks to the awful Vice City original handling.cfg.
Here are a few samples (I'm not finished with the Blista Compact, at the moment it's a bit of an experiment)
Infernus
The original infernus was terrible. It barely hit 100mph and it's supposed to be the fastest car in the game. I set this up to understeer slightly at very high speed, and oversteer if you floor it in a turn. It now goes like the Lamborghini Countach it was supposed to resemble.
Top speed: 160mph
Comet
The comet was originally supposed to be a 4wd Porsche 911. However this game is set in the 80s, when 911s were rear wheel drive, and oversteered due to their rear engines. Therefore I tweaked Cerbera's Porsche 911 setup to recreate the feel of an old Porsche.
Top speed: 120-130mph
Sandking
I set this one up to drive like a Paris-Dakar rally car, or a Bowler Wildcat. It has about 400bhp (I'm estimating here), a low centre of gravity, and 4wd. Its special 4wd system delivers 60-65% of the power to the rear wheels most of the time, so you can achieve incredible drifts, especially on sand. Like a Bowler Wildcat, it's incredibly strong, it can outrun most sportscars, but it's a difficult beast to drive.
Top speed: 130mph
Blista Compact
At the moment, this is a 'Blista Compact Evo' if you like. First i set up this Honda CRX clone realistically, then I modified it for front wheel drive drifting. With skill, huge drifts can be held, and you wont spin out. Tons of tyre smoke.
Top speed: 100-110mph.
my_handling_setups.txt