DETROIT MOTOR SHOW: Lexus goes M5 hunting, or does it?

Lexus has revealed its first full-blown F version of the GS and the first V8-powered version of its latest large sedan since the previous-generation GS 430.

The Japanese luxury brand's hottest ever GS winds up the volume significantly over the GS 350 F Sport on which it's based, featuring a far more aggressive exterior design.

The visual changes include a massive mesh grille, slimmer new three-element headlights above arrow-shaped LED daytime running lights, stacked quad exhaust outlets, a subtle bootlid spoiler and new front wings that combine with chunky side skirts that extend upwards behind the front wheel-arches to form front quarter vents.

Inside, there are sumptuous front sports seats with black/white perforated leather, integrated head restraints and embossed F logos, plus extensive carbon-fibre highlights, contrast stitching and metallic accents.

Mechanically, as seen in the teaser pic released in December, the GS F scores beefy orange six-piston front brake callipers, plus new staggered-width multi-spoke 19-inch alloys – nine inches wide up front and 10-inch at the rear – with 255/35 front and 275/35 rear tyres.

Lexus has now confirmed the top-shelf GS will have a stiffer chassis, sportier suspension and a Torque Vectoring Differential (TVD) with three different modes: Standard, Slalom and Track.

The same multi-plate clutch-based diff system is also available in Lexus' other F model, the RC F, which also employs the same wheels, brakes and eight-speed torque converter automatic transmission with four driver-selectable modes including manual operated via steering wheel paddles shifts.

Surprisingly, the GS F also borrows its naturally aspirated 5.0-litre V8 with both Otto and Atkinson combustion cycles directly from the smaller two-door F model without any performance upgrades. In fact, the flagship F car's outputs are lower at 348kW and 527Nm – versus 351kW and 550Nm at the same 7100 and 4800rpm engine speeds respectively (US spec).

Acceleration figures are not available, but given the marginally lighter (1780kg) RC F sprints to 100km/h in a claimed 4.4 seconds, the 1830kg GS F will hit Australia's legal highway limit in closer to five seconds.

Despite being the lightest in its class, it will therefore be slower and less powerful than all of its direct German competitors — all of which employ turbocharged V8s to produce more than 400kW and at least 680kW — including the BMW M5, Mercedes-Benz E 63 AMG and Audi RS 6, which can hit 100km/h in 3.9 seconds.

The news will disappoint those who expected the GS F to pack a more powerful version of the RC F V8 or even the addition of forced induction, as suggested by the 478kW/710kW twin-turbo 5.0-litre V8 seen in the Lexus LS-based TS650 concept revealed by Toyota Motorsport GmbH (TMG) in 2012.

As we've reported, any plans to turn the German-based TMG racing and performance operation into Toyota's equivalent of AMG have now been abandoned, and the GS F is further evidence Lexus is content for its F models to be positioned – in both performance and pricing terms – below their hotter European rivals.

Indeed, given the $133,500 RC F is priced 80 per cent higher than the $74,000 RC 350 F Sport, expect the GS F to command a similar price premium over the recently upgraded GS 350 F Sport at about $180,000 – making it substantially cheaper than its key German rivals and more in line with the Audi S6.

Nevertheless, Lexus is committed to expanding its F line-up and has promised to reveal two performance models at Detroit.

The other car could be a new IS F sedan, a production version of the RC coupe-based LF-C2 convertible concept seen at the Los Angeles show in November or a production version of the LF-LC super-coupe concept.

The belated replacement for both the LFA supercar and SC 430 cabrio has been confirmed for production in 2016 and will be aimed directly at the Porsche 911 and priced close to $200,000.

Lexus has trademarked the LC 500 and LC 500h names, leading to speculation of a range-topping new LS limousine-based two-door with 5.0-litre V8 and 3.5-litre petrol-electric hybrid powertrains.