I actually went to the filming of the NBC pilot (as opposed to the current history channel version) of top gear US (the one with Adam Carolla and that guy from some sort of HGTV show) and it wasn't too bad (better than the Australian version)
Sadly enough NBC didn't approve more episodes because they thought there wasn't interest in a new car show (the knight rider remake had poor ratings) and the contents of that episode will be forever buried
I wish Top Gear USA success, but I think using that name dooms them. Yes, we've had successful British TV imports like "Millionaire", "The Office", and (ugh) "Got Talent", but replicating the fabulous chemistry that exists between Clarkson, Hammond, and May seems impossible. Copying a Renoir, still leaves you with a copy. Using the TG name leaves some huge shoes to fill. I also can't see History allowing the huge production costs that make TG so great.
Even though they might not have such a big budget, they could still do interesting things.
In the NBC pilot they had opening footage of the Stig and the Ariel Atom being airdropped out of a coast guard c-130.
In the their cheap car challenge where they attached bungee cords to their cars and threw them off a bridge to see which cars (If I remember correctly this included the Porsche 928, Datsun/Nissan 280z and Pontiac transam or firebird) were well built, surprisingly the Pontiac was the sturdiest.
Also top gear producer Andy Wilman was there to give advice