Infiniti has rebuilt its Q45 flagship sedan to compete with the Lexus GS and LS 430, BMW 5 and 7 Series and Mercedes-Benz E- and S-Class, straddling a fine line between price and performance in an effort to appeal to the widest possible range of buyers.

A muscular 4.5-liter DOHC 32-valve V8 engine makes the new Q move. It pumps out an impressive 340 horsepower (an increase of more than 25 percent over the 2001 model) and 333 pound-feet of torque. Infiniti claims that, mated to a new five-speed automatic transmission, this powerplant rockets the Q45 from 0 to 60 in 5.9 seconds. But the all-new engine is only part of the redesign. Infiniti wants you to keep its new flagship on course, so it equipped the Q with four-wheel independent suspension, including a new multilink rear setup intended to improve handling, stability and steering feel. The new Q also has Vehicle Dynamic Control (VDC), Infiniti-speak for stability control system that uses brake pressure and suppression of engine torque to keep the Q in line. In addition, traction control and four-wheel disc brakes with ABS are standard. And just in case all this technology can't help you avoid an accident, dual front airbags and side-impact air curtains are also standard.

Additionally, Infiniti doesn't want its valued customers stopping on the side of busy or deserted roads to deal with a flat, so it included run-flat tires (available only with the 17-inch wheels) that can run 50 miles at 55 mph. An automatic low tire pressure monitoring system notifies drivers of a leak or puncture so they can seek help.

One feature of the new Q that Infiniti emphasizes is the power of its new seven-lens high-intensity discharge (HID) headlights. Other cool Q toys include power heated outside mirrors with turn signal indicators. There's also a 7-inch touchscreen LCD display that allows the driver to control everything from cabin climate to automatic door lock and headlight settings. The screen also supports the Q's DVD-based "Birdview" navigation system and, this is really cool, a rearview monitoring system. Wider and taller than before, the new Q benefits from a stretched wheelbase that's nearly 2 inches longer, yet overall length is the same. These changes have boosted interior cabin space and trunk volume so that passengers, especially those in the rear, have more knee, hip and headroom than before. While the rear passengers are lolling about on the same high-quality leather enjoyed up front, they can use the rear power seat adjustments to get really comfortable and the rear audio controls to make use of the 288-watt 8-speaker Bose audio system.

Real wood trim, a wood and leather-wrapped steering wheel and other luxurious appointments make the Q45 one of the world's premier super luxury sedans. And now that its performance has been boosted, it challenges the competition for top honors.