Gran Turismo 4/Cars

GT4 continues in its predecessors' footsteps by offering an extremely large list of cars; the PAL version, for example, features 721 cars from 80 manufacturers. There are differences in the car lists between the different GT4 regional versions, and some cars have different names, e.g. the JDM Toyota Vitz is known as the Toyota Yaris in places such as Europe and Puerto Rico and the second generation Mazda Demio is known as the Mazda 2 in the same places (PAL version only), and a well spotted example is the Opel Speedster which is more commonly known as the Vauxhall VX220. One notable omission of the game is that it does not feature some well-known car manufacturer names such as Porsche, Ferrari, and Lamborghini. However, RUF, a company that modifies Porsches, is in GT4. Some of the cars are multiple variations on a single base model; there are 20 different Subaru Imprezas and Legacies, 25 Mitsubishi Lancer/Lancer Evolutions, and 48 Nissan Skylines, including the Nissan GT-R Proto. One vehicle, another Skyline, is in pace car form in the "Guide Lap" licence tests and is also a prize car. There is also the GT Edition, which was the pace car without the pace car lights, and even more power (541 horsepower, the standard version packs 276). Each vehicle model has over 4000 polygons. Car prices range from about 2500 credits for basic 1980s Japanese used cars up to 4,500,000 (450,000,000 in Japanese version) credits for the top end (mostly Le Mans) race cars. Some special prize-only cars (such as the Pagani Zonda LM Race Car '01) are not visible in the vehicle showrooms, and a few do not have corresponding dealerships, and thus are unmodifiable, for example, the Formula Gran Turismo (F1 car).

GT4 is responsible for a few vehicle firsts in the Gran Turismo series. It is the first to feature pickup trucks, such as the Ford Lightning, Toyota Tacoma, and Dodge Ram. It is the first game in the series to feature the DeLorean, using the stage II spec engine (developed in 2004, hence the 2004 designation). It is also the first in the series to feature a diesel powered car, the BMW 120d. A special edition of GT4 featuring the 120d (and the rest of the 1 Series line), and three tracks were provided to BMW customers who purchased their 1 Series automobile before the release of GT4. While Gran Turismo 2 did have a one-off F1 engine version of the Renault Espace, GT4 was the first of the series to feature a production minivan, the Honda Odyssey (JDM version). A first-generation Mitsubishi Pajero Paris-Dakar rally car, a winner of the 1985 rally, makes an appearance as the first SUV in racing trim; the first SUV to appear in the GT series was the Subaru Forester in GT2 (although in fact the Forester can be racing modified). It was also the first in the series to feature D1 Grand Prix tuned cars such as Ken Nomura's Blitz ER34 D1GP.

The game includes some prize cars of historical interest, such as vehicles from as far back as 1886 at the dawn of the automobile. A special car called the Auto Union V16 Type C Streamline, built in 1937, can only be used in Power and Speed (which tests the performance of vehicles) or a test drive in Nürburgring, but interestingly has around 542 HP. Even some modern cars with complex body shapes cannot be raced against opponents, such as the Caterham Seven Fireblade. In Arcade Mode, these cars can be raced against a single opponent; this is the case for any convertible with the top down

There is also a special car which is specially tuned, called the 'Shuichi Shigeno' version of Toyota AE86, which is taken from Initial D, and is licensed by Toyota, although Toyota has never used the name of the author of Initial D. Comedian Jay Leno, an avid car collector, is listed in the game as a manufacturer; one of his custom cars, the Blastolene Special or "Tank Car", is included in the game as a prize car, available after beating missions 11-20. The 2022 Nike ONE has Morse code on the right hand side of the car. When reversed, this reads "www.phil-frank.com", the artist commissioned to design this car for GT4. There is also some Morse code visible on the inside of all four tires, but it is not decipherable.

GT4 retains all the familiar tuning parameters from the previous games in the series, but also allows weight to be added to the car. This can be positioned to affect handling or used as a form of handicapping. Another new vehicle tuning addition is nitrous oxide injection. Also, GT Auto can now install a rear wing on some cars, making it possible to adjust the car' downforce, which was previously only possible on racing cars or, on the first two games in the series, cars with the racing modification performed. The Suzuki Swift was present in its successor, Gran Turismo 5 but was known as a concept car in GT4, since the launch of the car was not official at the time of the game's launch.