Standard features for the SL450 include 19-inch wheels, a power windblocker, LED headlights and running lights, automatic high beams, headlight washers, automatic wipers, a panoramic sunroof, heated mirrors, front and rear parking sensors, forward collision warning and mitigation, keyless entry and ignition, cruise control, selectable drive modes and an adaptive suspension.
Inside, you get dual-zone automatic climate control, an auto-dimming rearview mirror, a power tilt-and-telescoping steering wheel, sun-reflecting leather upholstery, 12-way power, heated seats with four-way power lumbar and memory functions, tri-color adjustable ambient lighting, a navigation system with real-time traffic, voice controls, Mercedes' Mbrace emergency telematics, Bluetooth, the COMAND infotainment system, Apple CarPlay, Android Auto, two USB ports, and an 11-speaker Harman Kardon sound system with a six-CD changer and satellite and HD radio.
The SL550 adds a V8 engine, AMG-branded 19-inch wheels, a power trunklid with hands-free activation, a rearview camera, an automated parking system, the Airscarf neck-level heater, and ventilated seats with active side bolsters and massage functions.
The AMG SL receives a more powerful handcrafted V8 engine, high-performance drive and suspension settings, Active Body Control (mitigates body roll while cornering), upgraded brakes, a limited-slip differential, unique AMG gauges and other AMG-themed aesthetic flourishes, a dashtop analog clock made by IWC, upgraded leather upholstery and a faux-suede headliner.
At the top of the SL food chain is the AMG SL65, which gets a V12 engine, staggered-diameter wheels (19-inch front, 20-inch rear), adaptive LED headlights, the Magic Sky electrochromic dimming roof, soft-closing doors, adaptive cruise control, rear collision mitigation, blind-spot monitoring, lane keeping assist and a 12-speaker Bang & Olufsen sound system.
Most of the fancier trims' premium features are optional on lesser models. All SLs are eligible for a mobile Wi-Fi hot spot and many interior upholstery and trim upgrades. AMG models can be outfitted with carbon-ceramic brakes and carbon-fiber exterior trim.
Powering the 2017 Mercedes-Benz SL450 is a turbocharged 3.0-liter V6 that produces 362 horsepower and 369 pound-feet of torque. A nine-speed automatic transmission with manual shift control sends power to the rear wheels. Mercedes estimates it will reach 60 mph in 4.9 seconds, but that's the time we recorded in its SL400 predecessor with 33 fewer horsepower, so the estimate is likely conservative.
The SL550 pairs the nine-speed automatic with a turbocharged 4.7-liter V8 that's good for 449 hp (20 more than last year) and 516 lb-ft of torque. It can sprint to 60 mph in an estimated 4.3 seconds.
Ther AMG SL heats things up with a turbocharged 5.5-liter V8 producing 577 hp and 664 lb-ft of torque. It gets a high-performance, seven-speed automatic transmission. Mercedes claims a 0-60-mph time of 4.0 seconds.
Finally, the AMG SL65 keeps the seven-speed transmission but steps up to a turbocharged 6.0-liter V12 that churns out a prodigious 621 hp and 738 lb-ft of torque. Mercedes estimates it will reach 60 mph in 3.9 seconds.
EPA fuel-economy estimates stand at 23 mpg combined (20 city/28 highway) for the SL450 and 20 mpg combined (17 city/25 highway) for the SL550. The AMG SL is rated at 19 mpg combined (16 city/25 highway), while the AMG SL65 drops to 16 mpg combined (13 city/22 highway).
