"Without a 'direct cutin' into the antenna feed line, you get variable results - So is there a way to wire directly into the antenna feed line?"

There is almost always a technical way, but the amount of effort may mean it is not worth it. The hassle is that the player has no 'antenna output port' and the necessary hacking would negate the warranty, and make the thing look a real mess. Also you would need tiny elves to work on the thing due to modern size reductions.

The other way to attack the problem is to bring the car receiver antenna 'closer' to the transmitter. Again, the same sort of 'techie hacking' problems exist.

The simplest aproach to the solution may be this: the car antenna is outside the Faraday Shield that the metal car body is, so a more direct line of sight (thru glass) between the xmitter and antenna MAY assist the received energy at the antenna. This may mean placing the player on the dashboard (sun may damage it, and it is more visible to thieves), but you should try to fix (temporarily) it in place somehow - if the front windows are not wound up, it may fly out one when you turn a corner!

Didn't mean to steal your thunder answering techie questions JohninK, but this was obviously too easy for you! ... :-0