Is there such a thing? My FM range is pathetic on this car.

There's a good chance your antenna grid (printed on the rear window, above the defroster grid) is damaged. If you've ever had window tint installed or removed, be advised they USUALLY screw up the antenna grid. The conductive coating is very fragile, and can sometimes even be accidentally scraped off with just your fingernail. (Be very careful cleaning your rear window on the inside!) There'a also a connector that fastens to the rear window, and if that comes loose, reception will be poor on FM, and just about non-existent on AM.

Checking the grid and connector can be done visually, but it sometimes hard to see small "breaks" in the grid.

Well, the windows were tinted when I bought the car, but the connections are good. Perhaps the antenna grid is damaged as you say. I wonder if I could put a regular antenna up in the headliner, maybe.