This one is on Gran Turismo 3 A-spec.

First off, it is a racing game through and through, no flashy cut scenes, no driver details, no driver names. Just flat out buy a car, upgrade it, and race it.
The physics engine in GT3 is superb, with cars reacting to every bump in the road. You can customize ever detail of the car's performance, but with looks, it's the paint you buy the car with, or the rims, nothing more. If you mess up gear settings or suspension settings, be prepared to lose. Alot.
The number of tracks in GT3 is very good, with some world famous tracks such as Laguna Seca and the famous Monaco Formula 1 track. Seeing as every individual car handles differently, especially when modified, it can be an entirely new experience every time you race on a track.
When going to a race, you need to have the appropriate license, ranging from Super license which lets you into any race, to the C license which limits the amount you can enter. Obtaining the licenses is difficult, but worth it, as the prize money you receive from the higher races is substantial. There are also Rally races, with Rally cars based on actual cars used, such as the Lancer Evolution 6 rally car, to the Ford Focus rally car, and even the infamous Suzuki Escudo Pikes Peak rally car. Each has it's own personality, and some are downright monstrous in power.
Some cars are only obtainable through winning certain race events, such as the Stars & Stripes trophy, or the All Japan GT Cup. Or by completing leagues, such as the Beginners League, or Amateur League.
GT3 also has Endurance races, which are just that: long and difficult. With tire wear and 2 hours worth of laps, these races really test your skill and handling your chosen car against against the opponent.
Engine wear is an important factor, as with miles on the car comes with power loss. A fully upgraded Dodge Viper will have around 1000 horsepower, but after 600 miles, that power will decrease marginally. Oil changes can help fight the power loss, but it will never gain 100% of that power back.
All in all Gran Turismo 3 is a racing game that is for hardcore racers only, anyone else will find this game boring and unattractive.
I give it a 10 out of 10.