It seems unlikely that this is the final car list. Give it until the end of November to make final judgement.
This just a stream of observations.
Abarth's entire lineup is there. Nothing needs to be done here.
Alfa Romeo is missing the 4C (and the exact same team behind that car is responsible for the 6C Biposto Vision Gran Turismo Concept so this car's inclusion is damned well sealed in stone) and the Giulietta 1750cc.
Aston Martin is missing both its new DB9 and its new Vanquish and seeing that they are onboard the Vision GT program, I find it likely that Polyphony Digital will have access to these cars. Not to mention the DB3S which is currently having a virtual model built.
Audi is a tough cookie since they PAID Turn 10 to include their cars. It seems like Polyphony did most of their Audi deals in 2012, which is why we have the older R18 and not the eTron (not that it matters since Forza's eTron doesn't even use the KERS defeating the entire point of the car). And the R8 V10 plus and TTRS were at the Gran Turismo Silverstone event but those are both older cars compared to the new RS4 Avant, RS7 and RS6 Avant. We might be SOL on that front, but what we have is good enough. Then again Audi is a part of the Vision GT project, so maybe their relationship with PD is closer than I thought.
Bentley's relationship with Polyphony is very strange. They consistently get access to the 2003 Bentley EXP Speed 8 again and again and have never had a Bentley road car in game. Ever. Even in GT4 Prologue when we saw videos of PD walking around warehouses filled with Bentley's nothing ever came of it. I expect nothing on this front.
BMW on the other hand has two alternative powertrain vehicles coming out and we all know PD loves those kinds of cars. They are also part of the Vision GT program. And the trailer for the KAZ film shows that Yamauchi himself has been to BMW's very own museum. Also not how similar the BMW Vision GT's shape is to the i8. Could again be the same design team, meaning that the i8 may show up in game as soon as the production i8 is released to the public. I expect many things from this front including the E30 M3 everyone on GTPlanet has been harping about.
Bugatti on the otherhand may be a done deal. It seemed like the Veyron was already modelled in 2010 but couldn't make it in game since the disc was already gold by then. And PD seemed to have issues adding cars as DLC and future DLC cars had their information already in the game. If a Veyron Super Sport appeared I would be very surprised.
Caterham of Japan badly wishes t have a deeper relationship with PD as seen with their Tokyo R246 video they created. Why PD doesn't take them up on it I do not know, but Caterham seems ready and willing to have their cars in GT.
Cadillac has all the cars it needs in GT6. Not to mention with GM and PD's current relationship, if a new V car came out, I am sure PD could get their hands on it faster than even the automotive press.
Chevrolet is the same. I also expect to see two new Camaros (the ZL1 and Z/28) since PD has a close relationship with Mark Stielow (whose Red Devil is confirmed for in game) who was on the engineering team for both of these cars. Also the 1957 StingRay race car shows that PD has gone to GM's personal car collection and has free access to whatever strikes their fancy.
Citroen appeared on Kaz Yamauchi's personal Twitter last year when he was in Europe bouncing from headquarters to headquarters. The only car they even have to add is the DS3 Racing. I am unsure if they need the FIA WRC's permission to include the DS3 WRC or if that belongs to Citroen themselves. They never had a problem adding WRC cars before GT5 (they just never had the WRC logo on the sides of the cars themselves).
Daihatsu has a new Copen and seeing that this game is primarily Daihatsu's best way of getting their name out to the worldwide markets (not to mention it is a Toyota brand) this will probably be rectified soon.
Dodge/SRT's entire sportscar lineup is already in GT6 and nothing is really missing unless fans just demand that the Grand Cherokee SRT and 300C SRT end up in game. SRT is already on board with the Vision GT program which means they are happy to give their cars to PD. The Viper has been in a sales slump and SRT putting their cars into GT6 could help solve this problem. Also SRT's very own race car, the Viper GTS-R has had its Forza sponsorship removed last year, making this car's inclusion a possibility at the very least. Don't forget their new GT3 car.
Ferrari has me slightly worried. All of the "new" cars in Gran Turismo 6's lineup seem to have been taken from the 2010 Tokyo Concours D'Elegance event that happened exactly once and never again. And the FXX in itself is a rather old car. The F12berlinetta is a very odd car for PD to hide and I am starting to suspect that the car was never modelled to begin with. Also both Formula One car have been removed, possibly due to a very temporary licensing agreement for Gran Turismo 5 that didn't apply to GT6. Either way the turbo California, the 458 Speciale (which is a very new car so its forgivable) the F12, the FF and the LaFerrari (which still hasn't been sold to customers yet) are absent. That is right, Ferrari's entire current lineup outside of the 458 Italia is absent.
Ford is just missing the Fiesta ST. We aren't sure if PD has gone after the FPV Falcon's (who are going the way of the dinosaur very soon anyways), but PD has exactly one car missing. Their relationship with Ford seems healthy enough and they may get the next Mustang in game as soon as Turn 10 does in their's. We all know how much Yamauchi loves Ford GT's and all its variants (as much as he love Corvettes and Skyline GT-Rs).
Honda is giving PD early access to the NSX and if they create a new sportscar, PD will be the first to know.
Hyundai's entire sportscar lineup has been modelled when PD was at Cobb Performance's HQ in California. Also remember Rhys Millen's mention of PD modelling Pikes Peak on RedBull's website? This could be an indicator that Polyphony has had access to RMR's very own hillclimb Hyundais.
Infiniti is a no brainer. I expect the new Q50/Infiniti Skyline (as it is known in the JDM) to appear very soon.
Jaguar seemed very keen on throwing their cars to PD and Yamauchi was supposed to drive the new XKR-S GT at Goodwood before he got sick. The F-Type is too much of a success for PD to ignore and since they had/have such a close relationship, at the very least it should be DLC.
KTM has their entire lineup in game and seems to be happy to give their cars to any and all developers, just to get the word out that they are building cars. PD is happy to help.
Lamborghini's lineup in GT6 is literally perfect. I think the only thing they might be missing are the Reiter Engineering built GT3-spec Gallardos that race all over the planet. The Diable GT and Diablo GT2 are the EXACT cars seen in Lamborghini's very own museum, which means PD itself has been snooping Lamborghini's very own warehouse.
Lancia: Every car we need (except the Fulvia HF and the 037) is already in the game and PD's LM Gianetti visits are a good indicator that any gaps in its Lancia dealerships will be filled in.
Land Rover's recent inclusion could be a symptom of PD's good relationship with Jaguar.
Lexus has every sportscar it has created in GT6 already. Not to mention Yamauchi has alread been seen operating an LFA Nur. And PD has early access to the IS-F, meaning the GS-F soon to be shown off this year at the Tokyo Motor Show is not too far behind. It is likely already modeled. Toyota is quick to use Gran Turismo to market its cars so I have no fears Lexus will be left behind.
Lotus is a very strange case. We all remember how fast PD got its hands on the Evora and I expected more of a relationship as time went on, but nothing seemed to have come of it. We have never gotten an Exige in game, which is Lotus' most sporty car. And since Turn 10 now has Lotus' Formula One cars in its game, this may signify an end to PD and Lotus' relationship. I still cannot explain why the Exige's have yet to appear in a Gran Turismo.
Maserati needs to market their new Ghibli badly to get sales traction and GT6 would be a great way to do it. But Maserati's relationships with any videogame developers, never mind Polyphony seems very weak. I expect little to change and Maserati has more pressing matters at hand since it grows more and more irrelevant as time goes on. Rumors of an MC12 Stradale appearing in GT6 have been grumbled but rumors are just that.
Mazda is always ready and willing to give their cars to PD, so a new Atenza Sport and Axela Sport should not be far behind.
McLaren may have entered into a strategic agreement with Turn 10. NFS/Speedhunters has extremely early access to the McLaren P1 so they had first dibs. Turn 10 seems to have paid a lot of money to get special access to this car and may themselves be preventing this car from appearing in GT6, at least for the time being. Not to mention the vintage F1 car from Rush appearing in Forza 5. At the very least PD should be able to find an MP4-12C GT3 for the game. And with Ayrton Senna's family's blessing, some special licensing agreements with his McLaren could be a possibilty. As for the McLaren P1's inclusion, don't hold your breath.
Mercedes-Benz and AMG specifically have a VERY close relationship with PD and at the very least the A45 AMG and E63 AMG have been confirmed. Whether that is day one confirmation or DLC confirmation is up for conjecture. GT6's Mercedes-Benz lineup would look very odd seeing that is has no current cars (the SLS AMG was replaced entirely by the SLS AMG GT) so these cars not appearing day one would be a strange choice for PD. It seems all PD has to do is ask and they will receive whatever they want from AMG. Hopefully PD does just that.
Mini is another one of those brands just hurling itself at PD's doorstep. The Cooper Coupe S and the Cooper S GP are the only two missing cars, and Yamauchi races againts Mini's official VLN team every year.