Just like you can tame a wild animal to be more placid and controllable in a domestic environment, the writer is saying a powerful sports car can be 'tamed' as well. The sports car can be mastered or controlled so that it equally works on a suburban street as a raceway.

You'll hear phrases like tame, streetable and bad manners ,and what they're referring to is the fact that certain combinations of parts in an engine can make it not pleasant to the... depending on said drivers patience for instance it could that it doesn't create enough vacuum for power brakes or as soon as you come off the brakes it's lurching forward or even while on the brakes it's jerking or it has a really big cam or because the timing or idle speed is really high...and there is nothing you can do as a driver to tame it in stop and go traffic...it's just doesn't have good manners..it's a radical

Tame could possibly refer to the ease of handling. I think what they are trying to say is that there are sports cars which may have lower acceleration and better low gear performance which makes it easier to drive in the city. I don't think they're talking about getting more comfortable with the car though, it's probably more about how it behaves when driving slowly. Tame like Miguel said means docile but it can also be applied to wardrobe and other things like that so it can mean just "restrained" in a less literal way.

Thank you all who anwered my questions. One thing I am still not clear about is that the original two sentences are in the same paragraph, and there are the only two in it. It seems that the two sentences are isolated. What owners point out seems to have nothing to do with its previous sentence "Many sports cars are tame enough for ordinary city driving." Do you think so? Thank you.

Tame = docile, easy to control. It's like the author is comparing sports cars to wild animals, difficult to control.