The drop-top SL has several changes for 2017, including styling updates and more horsepower. The entry-level SL450's twin-turbo 3.0-liter V6 engine gets a boost to 362 hp and is mated to a new nine-speed automatic. The next step up the SL ladder, the SL550, is powered by twin-turbo 4.7-liter V8, now making 449 hp. The monster AMG models--SL63 and SL65--make due with 577-hp, twin-turbo 5.5-liter V8 and 621-hp, twin-turbo 6.0-liter V12 engines, respectfully. The SL is a luxury roadster with a foldable hardtop that's comfortable and quiet. One neat feature is a roof panel that offers varying degrees of opacity. Safety features include automatic emergency braking, blind-spot detection, and lane-keeping assist.