29 Special
The 29 Special, which is usually found painted pink, is one of the fastest cars in the game; it's nearly as fast as the police cruisers that chase you around. It's also one of the game's most maneuverable cars, and can sustain a surprising amount of damage.
Ambulance
The best way to find an Ambulance is by shooting or running over someone and then waiting for an ambulance to arrive at the scene. These boxy vehicles are terribly slow, but they can sustain quite a bit of body damage before being totaled.
Classic
The Classic is a classy sports car. It's hard to come by, and when you find it it's usually painted black. The car has a high speed rating, great maneuverability and it can take more than a few shots before running off the road.
Juggernaut
The Juggernaut is a surprisingly easy to come by tank-like vehicle. Unsurprisingly, it can sustain a ton of damage, but it's very slow and takes very wide turns, meaning you won't be driving it through city alleys while trying to ditch the police.
Porka Turbo
This fragile sports car has one of the game's highest speed ratings, but it can hardly sustain any damage. It's hard to come by, but you can spot it from afar due to it's bright green color.
Roadster
The Roadster is considered to be one of the best all-around cars in the game: it features high ratings in speed, maneuverability and damage-taking. Unfortunately, these are very hard to come by, so make sure to hijack it when it drives past.
Tanker
Like the Juggernaut, this oil tanker can sustain a massive amount of damage. The Tanker has very slow acceleration but it can reach a surprisingly high maximum speed. They're usually green or light brown.