Mercedes is launching a pair of new open-top versions of its AMG GT sports car, continuing its challenge to the Porsche 911. The base model, the AMG GT Roadster, comes with 469 horsepower (a modest jump from the 456 hp made by the base AMG GT coupe) and 465 lb-ft of torque from a 4.0-liter, twin-turbo V8 – that’s enough to get the car from 0–60 mph in 3.9 seconds and up to a top speed of 188 mph. For those who want something a little bit more “turned-up-to-eleven,” Mercedes also has the AMG GT C Roadster, which gets more output and torque (550 horsepower and 502 lb-ft) as well as a wider rear end that makes room for larger wheels and an active rear axle steering system brought over from the AMG GT R that lets the rear wheels turn in the opposite direction to the front. According to the Mercedes press release, it gives “significantly higher agility and increased driving pleasure with less steering input” – though the more usable benefit is a reduced turning circle. Both convertibles have a fabric roof (available in black, beige, and a gorgeous red) that can open or close in around 11 seconds and it can do it while the car is going 30 miles per hour. The two AMG GT Roadsters will arrive in dealers in the fall of 2017. Pricing was not disclosed. And be sure to check more world’s most expensive cars.