4 Good Speakers for Hyundai Getz

I own a Hyundai Getz GLS. It came with a Sony headunit and four installed speakers as a part of the dealer offer. I had an occasion to examine what kind of speakers they are. The two front ones are Sony X-plod (or atleast Sony X-plod lookalikes one gets these days in car-audio markets, since there is only a sticker with the name "Sony" on the magnet with no other markings). The two rear ones are Pioneer. Both are "three way" types. I am in general dissatisfied with their sound. I may mention that,

1.) I am not a bass-freak, and do not intend to install an additional amplifier or subwoofer inside my car.

2.) I do not play music loud in my car.

4.) I do not wish to do extensive re-wiring in my car for audio.

5.) If the four speakers alone can not give me very good frequency response in the car, let it be. I feel that it is the inherent drawback of in-car environment, which can not be significantly improved.

6.) But I wish whatever sound my car-speakers produce (within the limitations) should be very clean and distortion-free.

So in short, my requirement is only for four very good car-speakers that fit Hyundai Getz, to run with a Sony head-unit. I am willing to spend for this. It does not matter whether the speakers are Indian or imported.

Any suggestions?