Turbo's can be very reliable too. I had a Volvo 850 turbo for 11 years and 155,000 miles with zero problems. That engine was a 2.5L inline 5 cylinder. The turbo was tuned for low and mid-range torque rather than peak power at high rpm. It also had a "charge air cooler" or intercooler. Maintain a boosted car religiously and don't go screwing with high boost levels and my experience has been that the engines and boost systems are very reliable. Don't forget that superchargers and turbos have been on aircraft and heavy truck engines forever. Manufacturers have lots of data on component reliability and Mercedes didn't skimp on this engine.