Very well said JeffGoddin, hear hear!
In all seriousness, I can only agree with what the others have said. The Cultus is no more a cheat car than anything else when in certain contexts. Hey, when I first started playing GT2, back when I was like 9 years old, I had a used Prelude, and would enter it into the French Championship at Tahiti Road for relatively easy £££s early on, and I'd dominate those races - by the same term, you could say my Prelude was a cheat car for that race. Maybe cheat is the wrong word - maybe 'take challenge out of game' car is more appropriate.
I agree with JeffGoddin's sentiments though, and it's why now, I literally cannot overkill a race, unless I desperately need cash. But even so, I hunt for a good, close race wherever I can. The way the GT games are structured, it's pretty easy (less so in later games) to get a strong car before halfway through the game and tank a lot of the high-ranking races and endurances, therefore wiping a lot of the challenge out of about 60% of the game. Obviously there are still the manufacturer races and HP-limited races, etc, but even so with clever negotiation around the rules, it is possible to overkill these too. But where's the challenge in that?
I've long thought that Kaz makes Gran Turismo to be a celebration of teh car, and of racing. That's why he includes the rare, obscure cars - you may never race them, but that's not the point, you at least have the chance to drive them and enjoy them on an equal footing with, say, the supercars and Le Mans prototypes. That's why it always has a laid-back atmosphere to the menu screens, music etc. A NFS Carbon type atmosphere, for example, with lots of testosterone and egotistical characters strutting around mouthing off about 'taking you down' and other such horse manure, would not work at all, as that's not the point of the game. In Gran Turismo, you make your own adreneline rushes, and they can come in anything from a Daihatsu Midget to a Suzuki Escudo.
I know I'm veering off-topic here, but my point is, GT allows us this free-form structure, and it's up to us to choose whether we overkill everything and move on, or geniunely work hard to craft a close race and test ourselves to the limits of driver skill. I used to be in the former camp, but have now moved squarely to the latter, and have enjoyed some fantastic duels in the GT games, GT2 being no exception, with some of my most thrilling races coming from not behind the wheel of a GT-One or other high-powered car, but from a SilEighty, my humble Prelude, a Mazdaspeed RX7, and assorted other, relatively humble machinery.
Anyway, enough blabbing - my conclusion is that the Cultus is included in the game as a fine example of technological achievement for us to hoon around in, and for us to widdle all over the game as a challenge if we so want...but where's the fun in that?
) is the cheat car. However, I found that the Cultus is also a cheat car. Heck, I did win the Super Speedway GT All-Stars race with the Cultus. 
IMO the HKS dragsters could even lost with the Pikes Peak monsters. 
), or when I have to grind (coughxpcough), I do enter overpowered machinery. But I do it because I hate these stupid design choices, and I want to get it over with so I can do what I like in GT - driving cars for the sole purpose of driving them and appreciating the machine. Not repeating races over and over because a dev wants to extend the game length artificially.
,only wish there were more races it could compete in
