As you may recall, I am looking for a small automatic car for the g/f. Something recent enough to be safe. Got tempted by a Smart Roadster for a bit, but too small to be safe.
Found that you can get a 98-99 SLK for about £5K. Those are pretty good, right? 2.3K Auto, 80-120K miles, leeeaaaaathhhheeerrrrr. 
My opinion about mercs and slk's.
Slk's prone to go rusty on A pillar metal covers......i had the covers replaced twice on mine.
Did get told once on the slk if it has the side indicator repeators built into the door mirrors.....if the bulbs blow (its does have 3 bulbs tho) they carnt be changed.....its a new door mirror :-/
Merc make nice autoboxes....avoid the manuals.
If i was in the market for a merc......it would have to be silver , auto , full leather , climate (also in the case of the slk heated seats, peeps like to put the roof down on a sunny winters day....and still stay warm)
Reason for the above line....they are easier to sell on....people looking for 2nd hand mercs want these items
hth