We all had the same head-scratching with Gran Turismo 4 when the two Daimler machines and the Ford Model T were featured. There were some people on GTPlanet who were completely disappointed seeing that the lineup of cars included "antiques" like the two Daimler machines or that Ford Model T. Like cars with a top speed of 11 mph have no place in a racing game. Amid the crying and whining, I told people to take this more like a learning experience rather than feeling like you always need to race a Ferrari or a Koenigsegg. in a racing game. Then, take some of the Premimum machinery from Volkswagen in Gran Turismo 5. Those two military-type Volkswagen machines seemed a bit out of place for a lot of us who care more about maxing out the performance of a Veyron or trying to replicate the 6:41.000 lap time around the Nürburgring Nordschleife the Pagani Zonda R set.
Now with Gran Turismo 6, we get the 1971 Lunar Rover, and how do most people respond? This way: "what the heck is THIS doing in GT6?" Like I mentioned in the previous paragraph- what's wrong with a little learning experience? Yes- it's weird that a lunar rover is featured in a Gran Turismo game. However, it is an automobile. Maybe this is to provide a different experience. It isn't going to be one of those Red Bull prototypes performance-wise. Who cares? Why does every car have to be some speed demon? In one respect, you can say that unlike the Warthog (or whatever that thing is called- I am no HALO) in Forza Motorsport 4, at least you could actually use and operate such an obscure addition to a racing game like the 1971 Lunar Rover.
You can complain all you want about car lists in any Gran Turismo title. However, you can't dispute or disregard the learning experience provided with some of the vehicles. Gran Turismo isn't all "Nissan... then everybody else." Having machines like the Lunar Rover and such help establish Gran Turismo as an encyclopedia of cars. It may not all be the every-fastest-possible car game, but it is actually refreshing such a game features so many cars and even introduces you to many kinds of cars. From an education standpoint, I would have never known about car companies like Aston Martin, TVR, Ruf, Gillet, Hommell, Autobianci(?), or countless other companies and cars had it not been for Gran Turismo. GT has played a significant role in my loving and understanding of the world of automobiles. That even includes the Lunar Rover. Look at this more as a learning experience or "do I REALLY need to use space craft in a racing game?"
This is more a learning experience to me than for someone to think of the Lunar Rover as filler for the GT6 disc.