It isn't corrupt to give your supporters a ride to the polls. I guess I should qualify that by stating that it isn't corrupt as long as said supporters are eligible and registered voters. 
I've volunteered for a number of US campaigns, and all of the larger ones (i.e. anything more important than state senator) had programs to give people rides to the polls. I actually think it's a good thing. I know one time an 82 year old lady who wouldn't have voted otherwise was able to vote because someone from the campaign drove her to the polls.
