1999 Version...
Wasn't that in GT2 (the game and class)? The GT3 came out and the livery was updated to 2000.
For GT6 i'd like the Oreca to compete with fair opposition. It's always in the Le Mans race, or series with prototypes. yes it raced at Le Mans, but not in LMP or GT1. The Corvette GTS cars in the game, and my favourite, the Lister Storm should be performance balanced correctly, as the version in the game is a GT1 Lister Storm, and is slower than the Oreca Viper. However the real Lister Storm was raced in GT1 and GT2, whilst the GT1 car wasn't very good the GT2 car competitive against the Oreca Viper in 1999. Obviously the GT2 car is slower than the GT1 car, so why is the games GT1 Lister so slow?
Anyways, using these and some form Porsche/RUF GT2, there could be a GTS series on GT6, either that or class systems in races, IE can do Le Mans in an oreca Viper, but you'd only be competing against the other GT cars, not the LMPs.
Likewise, a Touring car series. Theres already a DC-5 Integra touring car, (which may or may not be based around Matt Neals 05/06 BTCC winning car) with similar specs to a BTC car, pretty sure BMWs 320 WTCC car is there. Add Seal Leon, Alfa 156, Honda Civic Type R, Polestar Volvo C30, Chevy Cruze, Vauxhall Vectra S2000 cars, and maybe a couple older BTC spec cars, such as Astra Coupe. Could even have Ai tweaked to "touring car" setting, where Ai's driving is much more aggressive, less mechanical sympathy or worry about tyre wear in short sprint races.
Haven't read all the posts, but Bathurst is mentioned alot, love that track on Toca games, definately needs the 1000KM Race, with V8 supercars.
Rally section needs a proper overhaul. Have rally and rallycross.
Add in new generation rally cars, Citreon DS3, Fiesta, Hyundai I20, Fabia S2000.
Finally, Snetterton as a track, for 2 reasons. Firstly it's my home track, secondly they can then add the daftness that is the Citreon 2CV 24 hour race!