I bought a 2003 CLK-55 AMG from a dealer in Kansas City.  It was star-mark certified and had low miles.

As others have pointed out, Mercedes has had serious quality issues.  The vehicle had a clean CarFax, but, as I was to find out, that is NOT very useful.

CarFax only reports DMV and insurance info.  They do not show DEALER or PRIVATE repairs.  The only reason I bring this up, is to illustrate how you can get screwed by a car dealer, even with a clean CarFax report.  This has happend to me on two cars now.

The CLK-55 had had extensive interior repair work and had been smoked in, even though the dealer told me point-blank that it had not (I later found cigarette butt rolling around under the seat).

The driver side door interior had been replaced.  The driver seat had been replaced.  Upon close inspection it was clear that the prior owner had a dog who had torn up the interior badly, but it had all been replaced by the dealer prior to sale and did NOT show up on carfax and was not specifically disclosed to me.

Now, on to the quality issues:

Day 2 of ownership:  Windshield gets a stress crack in the corner.  Not covered under warranty.

Day 5:  The car alarm goes off intermittently for no reason.  Happens while parked AND while driving.

Day 10:  Low washer fluid light comes on.  The fluid level is fine.

Day 12:  Low coolant light comes on.  The level is fine.

Day 20:  The third brake light literally disintigrates.  I do an online search and find out this is a massive defect in these cars.  The dealer said he would replace it, but only after I pointed out that I knew it was a factory defect from online research.  One CLK owner reported replacing his 4 times.  I happend to see another CLK in town, and guess what?  The brake light was also disintigrating.

Day 45:  The Mercedes emblem on the hood begins to de-laminate.

Day 60:  The CD player is reported by the car as 'not found'.

Day 61:  The CD player is working again, but stops playing intermittently.

Day 70:  Decided to sell the car...the warranty will be up soon and I can't afford to pay for the crappy quality.