Dammit I can't find it, but they guy got infected with nano machines, they showed them in his blood cells, and whenever he was in danger they reacted. One scene had him in a car and someone was tailgating dangerounsly, so his hand turns into a laser and zaps the car by bouncing a beam off the mirror, at the end he goes into full machine mode to rescue hmseolf and his girlfriend from the bad guy.
Dammit if I could just get the title down....
I don't know if this is the OP's film, but I think this is what you're thinking of.
It was a failed pilot with Scott Bakula called Infiltrator. Someone asked about the shooting another car with a laser bit on IMDb recently and I recognized the description.http://www.imdb.com/title/tt0163007/combined