Sports cars have been existing through the majority of the GTA franchise for numerous years. Sports cars usually outrun the rest of the vehicles, but may have difficult handling and usually a weak construction which doesnt allow them to to survive much damage. Most of the sports cars are also two-doors, which doesn't make them very good for drive-by. They are best used in races where their drawbacks are not so important. Majority of the sports cars are rare or unique, which only spawn in predetermined spots or are given as a reward from (side)missions. Some cars feature larger arrays of modifications, but mostly they range from those which are available on every car, such as nitro and wheels.
In GTA IV the performance and durability of cars has improved in comparison with earlier games.
This page lists various Sports Cars that appear in any Grand Theft Auto game.