While driving in a curved onramp connecting from one street to another the vehicle experienced a complete loss of steering ability which resulted in the vehicle continuing to move straight, off the pavement, and into a wall. The vehicle bounced off of the wall and loss of steering ability continued and the vehicle could not be controlled, crossed the road, went over a guardrail, and down an embankment until it came to a stop (approx 100ft). The vehicle engine never turned off until it came to a stop at which point the vehicle was manually turned off. No airbags deployed. There were no warning lights or signals of failing components prior to the loss of steering. An initial review by the body shop states that the vehicle is a total loss. The vehicle has been meticulously dealer maintained since the time of delivery as a new vehicle. The vehicle is pending inspection by Mercedes-Benz and by the insurance representative. The issue appears to be the same as those recalls described by NHTSA campaign number 18V872000 and/or 18V850000. The vehicle was never included in either of those recall campaigns. The vehicle is available for inspection upon request, but Mercedes-Benz is picking up the vehicle to perform its inspection.