Here's How Much Power a 402,000-Mile Mercedes-AMG E55 Still Makes

How does a hand-built engine hold up to interstellar mileage?

YouTube | LegitStreetCars

It's an accepted truth in the automotive world that putting almost half a million miles on a car ought to basically ruin it, doubly so if we're talking about a Mercedes-AMG E55 and its hand-built, supercharged V-8 engine. But how accurate is that belief? There's only one way to answer that question—strap it to a dyno and find out.

When the 2003 E55 AMG debuted, it was the quickest production sedan in the world at the time, with factory ratings of 469 horsepower and 516 lb-ft of torque. Time is not kind to any of us, but age alone isn't a killer for these cars—YouTuber and AMG specialist Alex Palmeri also tested a 2006 E55 AMG with only 69,000 miles on the clock and found it putting down numbers that roughly lined up with the factory specs.

But 400,000-plus miles? That distance can humble any car, let alone an AMG sports sedan that currently needs about $10,000 worth of work, according to a pre-purchase inspection Palmeri recently had done. The marathon Mercedes also wet the bed on a previous dyno run when a coolant pump failed and caused the supercharger to shut down. But with a new pump installed, Palmeri was finally ready to see what the old car had left.

After three pulls, he's got an answer: about 362 HP and 449 lb-ft of torque at the rear wheels. Since factory numbers are rated at the engine, and a car's drivetrain causes approximately an 18 percent loss of power, a little math yields the true comparison: this 400,000-mile Mercedes-AMG is still making 441 horsepower and 547 lb-ft of torque (exceeding the factory torque figure) at the crank.

Not bad at all for a finicky German luxury car that's already driven to the moon. It helps that this E55 is a one-owner car that spent its entire life in Southern California being serviced at a Mercedes-Benz dealership, and unfortunately we don't have any service records to show just how much money was spent on it over the last fourteen years. But it still proves that in general, cars are only as reliable as their owners.