The most extreme, the biggest engines, the loudest exhaust, this is what AMG is all about. Or at least, it was. Many people have criticized AMG for spreading itself too thin across the Mercedes lineup. We say the more AMG models, the better. But the name should be reserved for only the sportiest, most aggressive cars, not a bunch of overpowered crossovers and SUVs.

With the Black Series, however, Mercedes boasts a special line of models whose sole purpose to act a race cars for the street. Yet we haven't seen a new AMG Black Series model since the SLS Black Series went out of production in 2014. In fact, only five Black Series models have ever been created and Mercedes-AMG hasn't produced one for almost five years now. Which is why a used example could be a great investment for the future.

2013-2014 SLS Black Series

There is no greater proof that these cars can become collectible than the SLS Black Series. The SLS was the final Black Series to be produced from 2013 to 2014 and has reached collector status in just a few short years. The original asking price was around $230,000, but current values sit at around twice as much - we spotted several SLS Black Series examples selling for as much as $500,000. The cars weren't numbered, but production was limited with a reported 150 units being sold in the US.

Unfortunately, if you wanted to put one of these cars in your collection you are way too late to get one for a decent price. No one was paying over sticker price when the SLS Black Series first arrived, but collectors later learned how special this car could be. Gullwing doors, a naturally aspirated engine, a low production run, show-stopping appeal, what more could a collector ask for?

2009-2010 SL65 Black Series

Collectors may have missed the boat on the SLS Black Series, but there is another Black Series model with even more power that is now a relative bargain. The Mercedes SL65 Black Series was produced from 2009 to 2010 and was powered by a massive 6.0-liter twin-turbo V12 producing 661 horsepower and 738 lb-ft of torque.

Mercedes originally asked just under $300,000 for the SL Black Series when it was new, but you can now scoop one up at a discount for around $225,000. This may not be cheap, but it is a relative bargain compared to the SLS. The SL65 Black Series was limited to just 350 units worldwide, making this car the perfect candidate for a collector.

2012-2013 C63 Black Series

We wanted to talk more about the Mercedes C63 Black Series, but its collector value is a bit questionable. Of all the Black Series models sold in the US, the C63 is our biggest wildcard. Mercedes reportedly built about 800 examples, making it the most "common" car on the list. The car was originally sold for $125,000 and used prices range from around $80,000 to $100,000. The C63 Black Series does have the potential to rise in value, but we give it less of a chance than the other cars on this list.

2008 CLK63 Black Series

Since the US never received the SLK55 Black Series, the CLK63 Black Series is the oldest model on this list. Like the newer C63, the CLK63 was powered by an M156 6.2-liter V8, producing 500 hp in this iteration. Only 500 units were built worldwide with even fewer coming to the US. Prices currently range from around $75,000 to $100,000 and we could see them going for much more in the future. The CLK Black Series looked like a road-ready touring car, which means future collectors will love it. Jeremy Clarkson also famously owned one, which gives it even more credibility in the enthusiast community.

Future AMG GT Black Series

All AMG Black Series models have the potential to rise even higher in price, and the catalyst will likely be the introduction of a sixth Black Series model. When AMG finally reveals a new car with the Black Series name, it will be thrust back into the public consciousness, thus increasing the value of the old cars. AMG is rumored to be working on an even more hardcore version of the GT, which will slot above the GT R. If this car turns out to be real, we highly suggest buying one at sticker price and holding onto it while it skyrockets in value.