GM and their infinite wisdom could have made a hole in the body to access the serpentine belt tensioner My 2010 HHR LS shredded the serpentine belt after removing the plastic shrouds and the right tire to put a new belt on there was NO WAY to put a 3/8 drive on the tensioner to rotate it or access it thru the huge welded in body panel the only access is for the tensioner Bolt to remove it for replacement absolutely nothing to pry against to move it either. Redneck Job Hack: take a round pipe put it against the lower tensioner where it is closest to your Cam Pulley and use your jack to push it up and install your belt.
GM should of thought about this lil item before engineering this model year

 

$20 at harbor freight. Apparently there are other cars with tensioners that present a challenge.

I don't have it. Maybe someone knows if this works on an HHR.

 

I have a couple sets of the above ^^^ tool. One has metric sockets and crowfoots, the other has USA sockets and crowfoots. They work great.