I just tried something... you can use a Kart in BSpec Indy...

[Ben78]

So my "Bob" is in his Kart, going against a BMW McLaren F1 GTR Race Car.

And he won... my respect.

And still finished 12th. He's about 1 minute slower than the BMW per lap. I'll now try to see if I can enter a Kart in a free run online with normal cars.

 

[noisiaturismo]

And he won and finished 12th.

 

[Ben78]

Doesn't work. But it does work at least in BSpec online, but you cannot enter the normal ASpec and BSpec offline.