GT Hero 79...
I finished the game a while back and judging from what you've said so far, it seems like you've got way too powerful of cars to be racing Rolling Guy and Illusion B. So here are a couple things that maybe you know and maybe not that may help you get more enjoyment out of the game... none of these are meant to be insulting, the rules that come with the game are far less than helpful.
1) After you've beaten an opponent and the option comes up to either go back to your garage or continue racing (I can't remember exactly what that latter option is called), be sure to continue racing. This will allow you to race bosses and unlock new groups to race.
2) You can select different sections of track and different directions when you go to the highway selection screen. You can find new opponents that way.
3) The NSX and Supra should waylay anything you'll run into for a long time. So I'd honestly recommend restarting in order to get fun out of the game. If fun for you is leaving opponents in the dust, then enjoy the overkill.
4) One unfortunate aspect of the game is that it isn't in the least bit a good idea to purchase new cars unless you *have* to to fulfill Wanderer requirements or your car just isn't powerful enough anymore.
5) One good aspect, linked to #4, is that it is hard to raise money legitimately. So you really have to race a lot, especially prior to defeating Speed King, in order to get enough cash together to modify your car to compete with increasingly difficult competition. This turns off a lot of people, but I enjoy the difficulty more than having gobs of money thrown at me.
6) Another good aspect is that all cars and car parts aren't unlocked when you begin play. In fact, many of those parts won't be available until you've beaten given bosses. So you can't get too unbalanced early on (assuming you play a legitimate game).
7) It is very important to tune your car appropriately. One of the easiest - and I think mandatory - mods is to increase the car's response. You don't need to buy any modifications to do this, just go into your settings and change that to taste. I always increase my response to the fullest.
8) The best tips you can get for tuning cars in TXR0 is found in the descriptions of the various opponents you meet and defeat. It'll say things like "this guy has his car too low, so he has no stability" or "this guy has raised the rear of his car higher than the front to increase rigidity". Reading those will give you a great tutorial in how to make your car handle nicely.
9) TXR0 is all about drifting and/or powersliding. I frankly gave up on my stricter GT3 driving methods and it helped me a lot. It also made me a better GT3 driver in that I now use drifting when it can help me and I can control them better.
10) Live by the FAQs at gamefaqs, the manual that comes with the game is sparse at best and useless in truth. They also have a good - if a little xenophobic - forum there regarding the game. If you go to their forums, read as many threads as you can stand to before asking a question as a lot of the people there are less than patient or helpful.
Hopefully, this'll help you enjoy the game a bit more. If not, then trade it in at a used game store for something you like more. No game is for everyone. =D
That's the only way to do it.
They'll only race you under certain conditions.....your car is a certain color, certain day, must be driving a certain car, etc.
