Antennas need a good ground plane too, I would think best on a C would be somewhere on metal cab area, or possibly the rear bumper.
On my daily driver, my Camry Solara, I replaced the FM radio antenna with a CB antenna (a short 24" firestik to not look too out of place), then used a blocking splitter to hook the FM radio into the CB antenna, then tuned SWR on the whole setup, tuning SWR is almost more important than the antenna you choose. If you go the route I did, don't hook the FM radio direct into CB antenna you NEED the special blocking splitter so the TX power of your CB doesn't burn out your FM radio.
I plan on a similar combined CB/FM with a 2 or 3' firestik on our TV (the wife's daily driver, so she wont let me mount some huge antenna), but sadly for now we just travel with a crappy handheld CB with rubber duck, range sucks, but it DOES work and is better than nothing.
EDIT: I only monitor 19 usually, but my radio does have a scan feature, so sometimes I am scanning the whole band, but 19 is the only one with anything on it these days (unless conditions are good for skip, and then I turn the damn thing off because you will never hear any locals over the 1000 watt jerks shooting skip).
