I fitted a Hirschman (correct spelling?) whip aerial on the roof between the sunroof and the windscreen. It's the type of aerial that Peugeot and Renault use so you may be able to get on from a scrappy (about a two foot whip on a hinged mount). Carefully release the plastic trim which houses the sunroof switch/interior light which allows you to see the interior of the roof. Drill the hole, carefully, and taking care that the hole is in the middle of the roof (left to right wise, obvious really but...!) and the hole is about midway between the windscreen and sunroof. Make sure that there's nothing in the way underneath where you intend to drill the hole! Remove the near side door pillar trim and using a peice of stiff wire, fish the aerial cable across the roof lining. Remove the glove box and poke the aerial cable down the side of the dashboard moulding. Fish the cable out from behind the glove box and once the radio and cage is removed poke the cable round behind the heater controls and out of the radio apeture. Simples! Took me about an hour to do thats all and I get superb radio reception.
Humpy
PS The wifes car is a saloon and has excellent reception with the standard setup!