SPY PICS: Next Lexus limo

The new-generation Lexus LS large luxury sedan has been spotted undergoing hot weather testing in California's Death Valley, wearing fanciful camouflage to throw would-be sleuths off the scent.

The final design for the new LS is understood to be completed and could be shown as early as next January at the 2017 Detroit motor show, and the new model cannot come soon enough for the brand.

Going on 10 years old – overripe in automotive terms – the current car began production in 2006 and arrived in Australia in 2007, and Lexus has already admitted a replacement for its top-shelf luxury cruiser is overdue

However, as these spy pics show, the new Lexus flagship is being benchmarked against the new BMW 7 Series and Audi A8 -- and the current LS -- as the company works to bring a couple of surprises to pique the interest of well-heeled limousine buyers.

Expected to arrive bristling with high-tech doodads to outsmart its German rivals, including the possibility of semi-automated drive systems (think vehicle-to-vehicle and vehicle-to-infrastructure warning systems), the Lexus will ride on a new platform dubbed GA-L, or Global Architecture for Luxury vehicles.

This platform already underpins the large luxury LC Coupe and is the building block for the brand's upcoming front-engine, rear-wheel drive vehicles. It will allow the company to take advantage of new powertrains and technologies and provides a new canvas for fancy new designs inside and out.

The new look is tipped to borrow design cues from the Lexus LF-FC concept revealed at the 2015 Tokyo motor show, but that car's hydrogen powertrain is unlikely to be offered initially.

Instead, expect the same V8 – and, later, petrol-electric hybrid powertrains as the LC 500 Coupe, which packs a 348kW 5.0-litre V8 paired with an Aisin 10-speed automatic transmission.

There were rumblings of a downsized turbo V8 but Lexus appears to be focussed on its hybrid systems to bring emissions down. As such, expect the company's 3.5-litre V6 hybrid powertrain, featuring twin electric motors, to be the other powertrain offering initially.

These cars typically start at around $200,000 in Australia, the LS 460 kicking off at $185,000. Just 12 LS cars have been sold year to date, compared to the dominant Mercedes-Benz S-Class, which has found 174 homes thus far in 2016.

It's not yet clear when the new car will be on sale in Australia, but Lexus Australia spokesman Nick Raman told motoring.com.au: "Yes, the new LS will come to Australia, we just don't have timing on the vehicle."

Raman said the new model was an important luxury and technology leader for the brand.

The 2018 Lexus LS could find its way into US showrooms by the end of next year, but an Australian release is expected no earlier than 2018.