No this isn't as mediocre as you're thinking. It isn't. No it's not just another cheesy Hollywood comedy with dense jokes that's all about car-oriented action scenes and a pretty girl. I for example know nothing about cars and don't appreciate by the number American comedies and I really enjoyed this. If anything the title does the film no favors.
Dax Shepard, the male lead, actually does surprisingly well as a writer and director. Better than you'd think. In one word, this comedy has great 'balance'. The humor is centered a lot around contemporary social issues like political correctness and its abuse, and Shepard gives in a really good shift of managing to expose the silliness of the whole debate while not really piking any side outright and juggles well with both positions in a way that's properly comedic and fun. The character played by Bradley Cooper is characteristically hilarious in that same sense, he's this tree-hugging eco-friendly extremist psycho who acts as a spoof and as proper plot material at the same time.
Some scenes are genuinely funny, a couple proper hilarious, and all in all it's very well paced, very well constructed, dialog as explained is witty and balanced (not too cute, not too thick), the characters are funny and believable despite being like comic book characters, and there's good attention to detail, everything is spelled out or made totally obvious.
Very pleasantly surprised: 7.5/10.