Can you keep a secret? You can currently pick up a Mercedes-Benz folding hardtop convertible with an AMG-tuned supercharged V8 for $15k. The 2002-07 SL55 AMG is approaching peak depreciation. There is simply nothing else you can buy with this much wow factor and speed for this price.

Mercedes and AMG have an interesting history. AMG began life as a private German company that tuned cars such as Mercedes into aftermarket monsters. In 1990 it began to collaborate with Mercedes-Benz, offering its brand name as a badge on some cars available at Mercedes dealerships. By 1999, AMG had become a division of Mercedes-Benz. Its current status is much like Fords’ SVT department or Dodge’s SRT department.

In 2002, Mercedes was rolling out an all-new generation of its SL-class roadster. It was the first with a folding hardtop roof, and it would be the first SL with an AMG tune available in North America. For this “R230” generation SL, AMG decided on a supercharged 5.4-liter V8. Depending on model year and trim, it makes between 493 and 510 horsepower. It can also make up to 531 lb-ft of torque.

Car and Driver was understandably perplexed by the two-seat coupe with 510 horsepower. And understandably so. The German muscle car weighed in at 4,411 pounds. Though it’s a roadster, it is far from a Miata on the track. It was available with paddle shifters and lower suspension, but no three-pedal manual. If you want something cheap with good track times that’s supercar cool, you’d be better off shopping for a Lotus than this Mercedes.

But I’d say Mercedes knew exactly what it was doing. Testers found the SL55 could get to 60 mph as quick as 3.6 seconds. That’s enough to embarrass most modern cars at a stoplight. Rumor has it that when you remove the electronic top speed limiter, the SL55 AMG tops out at 208 mph.

This is a car built for cruising and highway pulls. And that makes perfect sense to today’s drivers. But what’s incredible about the supercharged Mercedes was that it came out over a decade before Dodge’s first Hellcat. You can see why Jeremy Clarkson had to have one as soon as he tested it.

Four Mercedes-Benz SL55 AMGs recently sold on Cars & Bids, a specialty site that often commands top dollar. Three 2003s for $16,250, $16,000, and $15,000. There was also a 2007 for $14,600. That is cheaper than a used V8 Challenger–let alone a Hellcat!

If you want a true supercar, with the unmistakable sound of a V12 engine, Mercedes has you covered. The most powerful non-AMG SL was the SL600 with a 5.5-liter turbocharged V12. This engine also was rated at 493 horsepower. But the torquey monster was rated at 590 lb-ft. Testers found it could also rocket to 60 mph in 3.6 seconds. So while you have to give up the AMG badge, and honestly probably lose some handling, you get the purr of a V12. And the wild part is that I’m seeing used ones currently listed at $20k. That really might make it the cheapest used V12 supercar around.

Next, find out why a used Aston Martin Vantage is the best deal in exotic cars, or see more cheap used supercar options in the video below: