Lexus IS250C and IS350C convertibles
Lexus revealed the IS retractable hard-top convertible, dubbed the 250C and 350C, at the 2008 Paris Motor Show. The two will show up before summer 2009, with a three-panel aluminum roof that opens in just 21 seconds. While the hood, headlamps, door handles and mirrors are common to the IS sedans, other body panels have been redesigned.
Like the IS sedans, the IS 250C has a 2.5-liter, 204-hp V6 mated to a six-speed manual or six-speed automatic transmission; the IS 350C uses a 3.5-liter, 306-hp with a six-speed automatic. Revisions to the body structure and suspension provide torsional stiffness and ride comfort with the top down.
Unlike many retractable-roof mechanisms that increase in speed due to the weight of the structure, a roof-brake mechanism slows the closing roof-panels as they approach the windscreen area, ensuring easy retraction just before closure.
A sleek aerodynamic design and a collection of underbody covers help achieve its lowest possible drag coefficient – 0.29 Cd versus the IS sedan's 0.27 Cd – while creating minimal wind turbulence on the cabin. An acoustic glass windshield, along with optimized seals on the roof, door and window panels, contributes to lower wind-noise levels.
A new fog-lamp design is integrated in the revised front air dam. The rear overhang increases by two inches to improve luggage space, providing storage for two golf bags in coupe configuration and one in a convertible. New combination tail-lamp clusters feature LED lights; a LED brake light is integrated within the standard rear spoiler.
The interior maintains the innovation and luxury touch points associated with the IS sport sedans, while new comfort and entertainment features provide a consistent atmosphere regardless of top configuration. Instrument gauges have been revised to help increase visibility during top-down driving, and the climate-control system has a speed-sensitive control feature that automatically increases air flow when the top is down while also automatically adjusting to vehicle speed.
The sound system has an equalizer-tuning feature that provides consistent audio whether the top is up or down, and it also automatically adapts to the natural loss of bass when the top is down.
With a four-seat configuration, the IS 250C and IS 350C's rear seats feature a center console with built-in cup holders. In addition to front doors that are 11.8 inches longer than the IS sedans, a new one-touch automatic mechanism provides easier egress and ingress through quick-acting, front-seat fold-and-slide activation. Rear-seat comfort is enhanced by shifting seat position inboard, providing improved headroom. The front seat backs are configured to also provide better rear-seat legroom.
All body and chassis revisions have gone through extensive testing to ensure that the IS 250C and IS 350C have nearly identical NVH characteristics as the IS sedans, while still providing a consistent blend of driving performance and comfort in convertible or coupe configuration. They share common double-wishbone front and multi-link rear suspension systems with the IS sport sedan models.
A number of body-structure changes have been integrated in the IS 250C and IS 350C to augment strength, roll-over protection and torsional rigidity. Active safety features from the IS sedans transfer as well, including Vehicle Dynamics Integrated Management (VDIM), Vehicle Stability Control (VSC), and an available Pre-Collision System (PCS). The Safety Restraint System (SRS) will include the twin-chamber passenger airbag, while a new enlarged seat-mounted side airbag helps provide additional protection in certain side-impact scenarios. The convertible body shell has additional energy absorbing side-impact materials that also help protect front and rear passengers.