As an American, your selection of automotive programming is quite limited. On one hand there is the SPEED Channel that is not available in every market, and on the other there is the "Powerblock" on Spike TV that offers little more than how to add a bit of power to your Grandmother's '81 Caprice.
Even as an import, Top Gear simply blew my mind away during my first viewing of the show last year when The Discovery Channel ran a season of the show slightly altered for the US Market.
For one, the personality of the show is unlike anything I have seen before. The show's lead host, Mr. Jeremy Clarkson is rather opinionated on everything, and although he will never hide the fact that he does not like something, he himself is quite likable as a person. On the opposite side of the spectrum, there is Mr. James May, quite possibly the most British man I have ever seen on television or in the movies. He isn't offensive in any way, and although he may be known as "captian slow," his presentations are quite enjoyable as they always seem to come from someone with a level head. Caught in the middle is Mr. Richard Hammond, a rather young Briton who embodies the current generation of automotive fandom. All together, the hosts balance each other out, and each offer their own perspective to the show, appealing to a wide range of people.
Outside of the "acting," the cinematography of the show is breathtaking, given that it is a weekly event in the UK. Occasionally the segments rival that of some of the best television shows or movies that I have seen, and although they are primarily focused on the car and the hosts themselves, the surrounding environment often plays a large role in the different reviews.
...But then you add the great soundtracks of the reviews, the quirky setups to the different tests (such as a Bugatti Veyron racing a plane from Italy to England), and the great test laps done by the Stig... It all adds up to one of the greatest television programs, well, ever.
It truly is a shame that the viewing of Top Gear is generally limited to the internet via You Tube or Google Video here in the US, but there was a pilot filmed for The Discovery Channel in the US for an American version of Top Gear, but thus far, nothing has happened.
If you have the time, I highly suggest you take a look at the show, interested in automobiles or not.