Mercedes-Benz dressed its E-Class sedan in sleeker sheetmetal for 2006, and revamped the interior to create the new CLS-Class. Sharing the E-Class's wheelbase, the premium midsize CLS wore a longer, lower, wider body that seated four instead of five. Unlike the E-Class, the CLS lineup did not include a wagon or all-wheel drive. The CLS500 had a 302-horsepower 5.0-liter V8 engine. For higher performance, the CLS55 AMG held a 469-horsepower supercharged 5.4-liter V8. Both used an automatic transmission: a seven-speed for CLS500, a five-speed for the CLS55. Each had a manual shift gate; steering-wheel shift buttons were optional on the CLS500, standard on the CLS55. Both models came with antilock four-wheel disc brakes, antiskid/traction control, and an air-spring suspension that adjusted firmness within three driver-selectable modes. Braking was handled via Mercedes' "by-wire" control, designed to vary brake pressure for each wheel as needed. The CLS500 had 18-inch wheels. The CLS55 came with 19-inch wheels, larger brakes, firmer chassis tuning, and cosmetic touches developed by Mercedes' AMG performance division. An AMG Sport Package for the CLS500 included wider tires and aero body add-ons. Front and rear side airbags, and head-protecting curtain side airbags, were standard; so were a full-length center console and twin bucket-type rear seats. Ventilated front seats were available, as were Mercedes' drive-dynamic front seats with air bladders that adjusted firmness to match cornering force. Also optional were steering-linked bi-xenon headlamps and cruise control designed to maintain a set following distance. A navigation system was available, as was Mercedes' Keyless Go locking/engine-start system with a pocket transmitter. Nothing in the premium midsize sector looked anything like the stylish low CLS, but its ostensible competitors included the Acura RL, BMW 5-Series, and Infiniti M45.