the C320 engined car is not so great performance wise, some actually like the C240 six engine better. The C320 is soon to be replaced or sold in addition with the C350.
The price of the C320 are high especially when compared to what you can buy a C230 for. In Calif till the end of the year C230 sedans can be had as some people have written on
www.edmunds.com for thousands under invoice.
Which ever C class you look at check to see if German Bremen made or Brazilian made. I like he German made better.
The 2005 C class sedan has been well received in the press and by some BMW owners. The 2005 C230 is a very nice car considering the AMG style bodywork and the low price.
Have the leak on the E diagnosed, could be a simple rubber gasket for the dip stick.
What the market holds for 100K mile W203 c-classes? well they have made over a million of them, the quickest made and most sold model of any mercedes sedan or coupe.