Judges aren't arbiters of truth, they're arbiters of law. If your standard for truth is "a judge didn't say it was legally defamatory", I hope nobody ever trusts anything you say.
Oh no! They showed a dramatization of running out of power while driving it on their track! How dare they!
(while driving around the track, cornering) "This car then really was shaping up to something wonderful. But then..."
(cut to Jeremy in the Roadster, a musical cue cutting off the soundtrack, signalling a problem. Jeremy pumps his foot, looks down at his foot and back up with a perplexed look on his face, and says "Oh", with backround noise of the Tesla decelerating.
Jump to outside view of the Roadster rolling to a stop in the middle of the track, with Jeremy narrating "Although Tesla say it will do two hundred miles, we worked out that on our track it would run out after just 55 miles." During this the scene changes to men pushing the Roadster in a hanger.
More narration from Jeremy, "And if it does run out, it's not a quick job to charge it up again."
Make of that what you will, I don't think words do it justice, which is why I included the video[0]. The narration is accurate, but the portrayal clearly implies something more than the narration, making it very to misconstrue what the facts are. The facts are, by the way, that the Roadster never ran out of power, they ran it for a few hours, decided they didn't want to wait for it to run out, and staged that portion.
Now, Top Gear is clearly an entertainment and comedy program, but to act like that's the end of it is also clearly ignoring the reality of the situation. Top Gear is less like SNL than The Daily Show or The Colbert Report. Viewers expect it to not be too serious, but right or wrong, they also expect to be able to get some information from the show, knowing that they'll need to sort through the context to determine whether it was a joke or not.
Keeping all that in mind, to me Top Gear seems to have overstepped slightly here. Then Tesla overreacted with a lawsuit. That's why I said neither seems to have come off well.
[1]: http://www.topgear.com/uk/videos/electric-shocker, start at 4:17 for the relevant scene.