Listening to noise don't sound like much fun to me, but I get it sometimes too.
Since your mobile does about the same in your drive way, it could be you're in a dead spot. But, on-the-other-hand it seems as though you would have already known that before...unless you just put up your station recently.
To tell the truth though, I don't hear near as well anymore either, but it could be a serious lack of traffic. I think two-way radio is rapidly dying on the vine. I live in Houston, and I talked to a guy in a mobile just today. He said I was the only station on 27.385 lsb that he had heard for 50 miles coming from the Texas Valley and heading home east of town.
CB seems to be dying out just about like the hula hoop craze did.