Uh oh, those DC to light "boosters" have a bad habit of dragging in all sorts of hash, mash and trash and are no substitute for a good receiver and antenna. Now here's the so far unasked and thus unanswered question; is this poor reception a recent development or are you simply disappointed in your car radio? If the former I suspect a fault has developed in the antenna mount and/or coax, if the latter I suggest a high end after market whiz-bang stereo.
Some auto makers supply great radios that'll knock your socks off while others are just plain crap and that's not limited by the make, some models are better than others too. Just to give an example, a friend's Dodge Neon surprised me, not only was the FM section hot but the AM was too PLUS my ears told me it had an effective noise limiter and synchronous detector that eliminated selective fading just like a high end shortwave receiver. Meanwhile the one in my Toyota sucked raw eggs all the way around and almost never got switched on.