The 2008 Mercedes-Benz SL-Class gets no major changes. These are Mercedes's costliest convertibles. They seat two and have a power-retractable hardtop. Four models are available. The SL550 has a 382-hp 5.5-liter V8 engine. The SL600 has a 510-hp turbocharged V12. The SL55 and SL65 are tuned by Mercedes's AMG performance arm. The former has a 510-hp supercharged V8, and the latter uses a 604-hp turbocharged V12. SL550 models have a 7-speed automatic transmission. All other SL-Class models have a 5-speed automatic. All SL-Class models have Mercedes's ABC active suspension that's designed to reduce cornering lean. Also standard are "by-wire" antilock brakes that can modulate brake pressure to each wheel. Other available safety features include traction control, antiskid system, side airbags, driver knee airbag, and a rollover bar designed to deploy in an impending tip. Also standard are navigation and assistance systems. Adaptive cruise control is optional.