The Mercedes-Benz R63 AMG is an unusual beast – a growling monster wrapped in a minivan body. Under its modest, people-carrying exterior lies a roaring 6.2-liter V8 engine, capable of producing 503 horsepower and 465 lb-ft of torque. A rare combination, to say the least.

This unique vehicle offers six seats with all the luxury you’d expect from a high-end Mercedes-Benz, delivering power to all four wheels. It’s one of the purest expressions of a “sleeper” car on four wheels.

Only 200 of these unicorns were ever produced for the global market, making it not just the rarest of the R-Class line but also one of the rarest AMG models ever created. It’s believed that just over half of these were brought to the US, so their owners truly possess a treasure. This could explain why their value remains above $30,000, even nearly two decades since their sole production year in 2007, and why this particular example sold for $50,000.

Now, here’s the intriguing part about a car like this: maintenance costs can be astronomical. This specific R63 has incurred approximately $42,500 in maintenance expenses since the beginning of 2019, with a single invoice totaling $17,020.06. This included the replacement of rivets, a job that took around 25 hours of labor. During this process, the owner decided to enhance the vehicle with Weistec Engineering parts, including a $4,495 exhaust system. Their attachment to this car is evident.

With a service history spanning 78 pages since 2015, this R63 has had extensive work done. On the bright side, it’s likely one of the best-maintained examples available today. Interestingly, this particular car has been modified for improved performance, reportedly generating 623 horsepower and 552 lb-ft of torque. However, there are no dyno tests to substantiate these figures.