The tuner isn't really the issue. I've used several (pinnacle, EVGA, Hauppage) and they all work well, provided you have a strong signal.
And that's the problem in a car. Short of mounting a home antenna on your roof, most of the "portable" antenna solutions don't work all that well. In most cases, assuming you have an external antenna of some kind, you can get reasonable reception if you are stopped and fairly close to the signal source. Forget about using it on the move...it's just doesn't work very well.
I use a full-size set of rabbit ears in my truck and get "OK" reception in most areas of town, if I'm stopped. Moving, I get exactly 1 out of about 15 stations in Las Vegas. And that one is in Spanish, which I flunked out of in 8th grade (too too many years ago).