The engine may develop a stalling and/or no start condition due to a failed crankshaft position sensor.Google+
Car Problem Reports
Mercedes-Benz SLK280 Engine Performance Problems Due to Crankshaft Position Sensor Failure
Mercedes-Benz SLK280 Problem
Visitor, 2007 Mercedes-Benz SLK280
Intermittent start issues. Can drive all over town, then stop and will not start back up. Dealership's service department can't figure out what's happening...it took a foreign car mechanic not affiliated with the dealership to figure this out.