I won't buy the car if the empeg can't be fitted in a reasonable way .

Well that brings everything to the next point, there are many small hatches in Europe with proper Din-sized openings where the Empeg will fit in a more harmonious way than in the Punto... the new VW Polo comes immediately to my mind, also the Peugeot 206... but my first choice would be the Polo , indeed. Of course, dinamically they are beached whales compared to a 206 GTi or your Punto, but build quality and sound isolation are far better. But then again it's your decision, good luck.