The current Lexus GS luxury sedan has been on the market since the 2006 model year so it’s not surprising the first development test-mules for the next-generation model, due late next year, have been spotted. And the new car can’t come soon enough given the recent launch of the new Mercedes-Benz E-Class and BMW 5-Series, and the next-generation Audi A6 is just around the corner.

Hidden under the sheet metal of the current GS seen in these latest spy shots is a brand new platform, expected to be sportier and more efficient. Overall length is expected to shrink slightly, although the wheelbase should remain at 112.2 inches. The modified wheel arches seen here also suggest that a slightly wider track will be present on the new Lexus GS.   

Fuel efficiency will be the name of the game for the 2012 Lexus GS, with a downsized V-6 engine expected to replace the current 3.5-liter mill as the entry-level option and the 3.5-liter engine going on to replace the current 4.6-liter V-8. A hybrid model will also return, most likely based around the entry-level V-6 engine.

Performance fans shouldn’t be too saddened over plans to scrap the regular V-8 model as a high-performance GS-F model will be offered for the first time. This car won’t pick up the high-revving 4.8-liter V-10 of the LFA supercar as previously reported, however.

Instead, it would pick up an uprated version of the 5.0-liter V-8 from the IS-F, developing around 450 horsepower and set to go on sale in 2013. Special features would include a torque vectoring differential on the rear axle and plenty of carbon-fiber to reduce weight.