Okay, first poll apparently self-destructed from editing the question format, so trying again.
So, this is just an interest of mine to see what can be done and just like the idea of being able to use a wheel and pedals with all my consoles for racing and similar games. However, I know I have heard interest from about four other people in using an actual racing wheel on the 5200, so I wanted to see how many other people share this interest and have wheels they could use to try out such games. For instance, how analog versus digital gas/brake with pedals works or how well/centered the steering is, etc. I got such a thing working well with a playstation to PC gameport adapter, a mad catz universal racing wheel and a couple adapters, but it is not something easily obtainable or inexpensive, while good gameport PC wheels are often under $50 total with shipping or at a local thrift shop and a lot of people already have bohoki adapters.
Right now, for racing games, there is only pole position and pitstop, but I know a couple other 8-bit games have been talked about for conversion. Games like Asteroids also fit well with steering wheel and pedals, since if gas pedal is set to up, it is thrust, along with some others. Now, recently, Video61 came out with an Asteroids unoffical sequel called "Megaoids," which is quite interesting. It can also add a little barely noticable exercise to your gameplay. I've been looking into programming some and would find hacking this sort of thing interesting, although it could be a year or so before I am adept at it. I've also considered checking wheels and fixing if necessary and selling them, if there is interest, but of course the shipping cost is a consideration in not losing money yet keeping it affordable.
Edit: I rambled on about wheels and pedals but the paddle mods and pc ultra-racer are fun when you dont want to drag out the wheel. Ive used these a lot along with the PlayStation Puchi Carat controller. I think the main barrier to the wheel and pedals experience is games where acceleration is up. Also, a flight yolk with pedals and triggers on the yolk handles would be more ideal for those drive and shoot games like Car Fighter.