What to look for when buying a W211 Estate

Hi all

As per the title, I'm thinking of buying a W211 estate 1.8 Kompressor or 220 CDI with 7 seats. Probably 03-05.

What do I look out for?

Is there anything that's a real bug bear with theses cars or mightily expensive to fix when it goes wrong?

It will be my first MB to own altho I've been lucky enough to drive an SLK55 AMG and a C63 AMG. I reckon the 1.8 Kompressor or 220 CDI that I'll be buying will be ever so slightly different :rolleyes:

Thanks

RG