IS 250/350: The rwd sedan was redesigned for the 2006 model year; a coupe is in development, likely for the 2008 model year.

A convertible was expected to debut when the coupe arrived. But Lexus is worried that its planned convertible may not succeed in a world of hard-top convertibles. The model may be sent back to the drawing board, forcing a delay.

Lexus executives downplay reports of a V-8, saying the big engine would kill the car's handling - not to mention that a 300-hp V-6 is plenty for a car this size. Don't rule out a hybrid as a midcycle addition.

Lexus won't comment on it, but our latest spy footage from Death Valley reveals what looks to be an even higher performance version of the Lexus IS 350 sedan.

Rest assured that whichever route Lexus takes, the IS 500 will stand as its most aggressive move yet toward unseating the Germans in the performance sport sedan segment. And if you don't believe that, consider this: the Lexus LS 460 sedan that goes on sale this fall will be the first model in the lineup to allow full disengagement of the traction and stability control systems. Don't be surprised if the IS 500 is the second.

Where that power is going to come from is the big question and there are two possible scenarios. The most likely source is a retuned version of the 5.0-liter V8 set to debut next year in the Lexus LS 600h, a hybrid version of the company's flagship sedan. With the help of its electric motors, it rated at more than 430 hp. Our sources in Japan tell us that Yamaha, a corporate partner of Lexus parent Toyota, will retune the V8 for use in the IS 500. Combined with a paddle-shifted version of Lexus' new eight speed automatic transmission, the 400+ horsepower IS 500 is expected to have a zero-to-60 time under five seconds along with a top speed of 155mph.

Although the use of a V8 in the IS 500 seems likely given its competition, other reports suggest this may not be the preferred route. A recent article in Automotive News has Lexus executives dismissing the idea of a V8 saying, "it would kill the car's handling." With that mind, Lexus could take a different route — hybrid power. By retuning the current 3.5-liter V6 and adding electric motors, the IS 500 could achieve the necessary horsepower targets without putting all the extra weight up front. It would also give the IS 500 the traction of all-wheel drive like its Audi rival. Lexus has already shown the performance capability of hybrid power in its GS 450h sedan, a car which outruns its V8-powered stablemate by combining a V6 with electric motors.

Rest assured that whichever route Lexus takes, the IS 500 will stand as its most aggressive move yet toward unseating the Germans in the performance sport sedan segment. Look for an official debut by the end of the year with sales beginning in 2007.

One look at this car and you might think it was destined for the SEMA car show later this month. But it was actually created by the folks at Lexus Australia for the upcoming Australian International Motor Show.

The chrome IS250 is the brainchild of the Lexus After Sales Division. In addition to the paintwork, the IS250 has been fitted with a new Lexus body kit - consisting of front lower spoiler, side skirts, rear lower skirt and a boot spoiler - which Lexus plans to introduce as a genuine Lexus Accessory late in 2006. It also features custom black aluminum wheels. Full image after the jump…

LOS ANGELES - Lexus will launch a performance brand in late 2007 to compete with Mercedes' AMG and BMW's M divisions.

Lexus will start with an IS sedan equipped with a 425-hp, 5.0-liter V-8. The engine is a retuned version of the LS 600h L hybrid's engine, dealer sources said.

The sedan will be called the IS-F. It will debut at the Detroit auto show in January.

Lexus likely will carry that nomenclature into other high-performance Lexus vehicles, a dealer said. He said a GS-F sedan and IS-F coupe likely will follow.

The IS-F - "F" as in "fast" - will go on sale in December 2007 and sticker in the low $50,000 range, sources said. Lexus told dealers of the plans at a recent national meeting.

Toyota Motor Co. filed for a trademark for "IS-F" on Nov. 8 with the U.S. Patent and Trademark Office. It also filed for a trademark for a stylized "F" logo on Oct. 9.

A dealer source said Yamaha is tuning the IS-F engine's heads for more power. Brembo will be the brake supplier.

Lexus declined to comment.

December 6, 2006 – Lexus will stage the world premiere of the 2008 IS-F sport performance car and an exciting concept vehicle at a press conference at the 2007 North American International Auto Show in Detroit.

The IS-F is an all-new high-performance version of the popular Lexus IS 250/350 sport sedans. It will feature unique styling and a substantial boost in power from a V8 powerplant that will captivate performance car enthusiasts when it goes on sale next year. In addition to the IS-F, Lexus will unveil an exotic sports concept.

The press conference will be held on Monday, January 8 at 11:25 a.m. EST in the Riverview Ballroom in COBO Center and simulcast live to the Lexus display area at the show. A video clip of the press conference will be available via the Lexus.com and pressroom.lexus.com Web sites immediately following the event.