I have partial video if this incident. Incident occurred at 991 odometer miles. After driving approx. ~300 mostly contiguous, flat, rural highway miles in-between Lincoln, ne and St. Louis, mo (heading to atlanta, ga) in approx. 30 weather on dry pavement, the engine stopped producing enough engine power to propel the vehicle at the 70-75 mph that I was traveling. At approx. 60-65 mph, I applied additional pressure to the gas pedal which was not effective. Pushing the gas pedal to the floor did nothing except, occasionally, the transmission would switch quickly in-between the same two gears, which registered slightly on the tachometer but did nothing to accelerate the vehicle or maintain speed. It almost felt as if the traction control was activating (but malfunctioning) despite the ground being totally dry. By approx. 50 mph I was being flanked and tailgated by two clearly disgruntled semi-trucks as I tried to pull over to the right. The vehicle seemingly would maintain a max. Of 35 mph. Upon restarting the car (normal start), letting it idle (normal idle), and then attempting to drive to a safer location, its acceleration felt restricted at lower rpms, but it did back up to highway speed and the restricted feeling ended up being temporary. The nearest dealer was mb of marion, il., approx. Another 200-300 miles away. On the way to this dealership, the same malfunction occurred again about 50-75 miles later. I went through the same process and restarted the vehicle. At the marion, il dealer, the mechanic found the following code in the computer: PO29921 - boost pressure of turbocharger too low. The mechanic at the marion, il dealer and, later, at another dealer closer to where I live (Mercedes of South atlanta) was not able to replicate this code and therefore no repairs have ever been attempted or made. This issue has not re-occurred here in Georgia.

- Stockbridge, GA, USA