It's a widely-known fact that all movies based on Saturday Night Live characters pretty much suck. OK, so it's not exactly a fact -- but it is a universally-held and widely-shared opinion, which is pretty much the same thing, isn't it? (Obviously The Blues Brothers is exempt from this rule, being that it was the first "SNL movie," it was directed by an actual filmmaker, and it rocks.) For the record, the SNL movies I'm generally referring to are titles like A Night at the Roxbury, It's Pat, Superstar, The Ladies Man, Coneheads, etc. -- stuff that made for perfectly entertaining 5-minute skits, but suffered mightily when stretched out like so much Silly Putty.
An SNL film through and through (although the characters were created specifically for the flick), Akiva Schaffer's Hot Rod is a whole lot like an entire episode of Saturday Night Live: A few stray moments of bizarre wit, clever satire and amusing weirdness -- couched between a whole lot of filler that's either A) not funny to anyone besides the performers, or B) almost painful to witness. Lead actor Andy Samberg clearly has some comedy chops and a gift for the disarmingly strange, but based on what's found in Hot Rod the guy seems better suited for a cable TV variety show than for feature films.
The screenplay reads exactly like a Will Ferrell movie down to the slightest touch of silliness: A petulant man-child called Rod Kimble fancies himself a mega-awesome stuntman -- despite the fact that he has no discernible skill at the craft. But it gives Samberg several opportunities to fall down and behave like a clueless dolt, so I guess the concept works as well as needed. Kimble has a crew of dopey pals, a beautiful love interest (of course), and a disapproving stepfather who needs $50,000 for a heart transplant. So clearly you know where the movie's headed, plot-wise.