Lexus continues to evaluate the next-gen LS on the road, and this time it has some rivals along, too. The engineering team clearly wants to check how the brand’s new flagship sedan performs in Death Valley against competitors like the current LS, BMW 7 Series, and Audi A8L.

The more angular styling on last year's LF-FC is a preview of what to expect from the flagship sedan's new look, but Lexus’ engineers continue to dress the LS in bug-eyed headlights and tail fins during testing in public. Don’t expect either of these hideous styling cues to appear on the production model, though. For a better idea of the rear’s actual shape, check out the photos with the trunk open because it’s a more realistic depiction of the back’s contours.

We haven’t seen photos inside of the new LS yet, but a top executive promised “cool interior stuff” that the brand had never done before. We think tech like a digital instrument cluster and gesture recognition could be possible. Customers should also expect the brand’s latest driver assistance systems.

Lexus won’t do anything too revolutionary with the LS’ powertrain at first. It will carry over the LC’s offerings of a naturally aspirated 5.0-litre V8 now with 471 horsepower and 398 pound-feet torque, or a hybrid 3.5-litre V6 with a total system output of 354 hp. However, there will be a hydrogen fuel cell version before the Olympics in Tokyo in 2020, according to rumours.

The more futuristic styling and upgraded tech is what the LS needs to get buyers’ attention again. The current model only looks stodgier in comparison to more recent luxury sedans like the Mercedes-Benz S-Class and latest 7 Series. Lexus has delivered just 3,768 of them in the United States through August, which was down 22.5 percent from the same period last year. For the entire 2015 calendar year, the brand moved 7,165 of the sedans – a 16.3-percent drop from 2014. In Canada, 55 have been sold so far in 2016. A total of 123 were sold in Canada in 2015.

The replacement for the Lexus LS flagship luxury sedan is now “overdue” according to Lexusexecutive vice president Mark Templin.

Templin played down suggestions that the eye-catching LF-FC concept sedan shown at the 2015 Tokyo motor show gave any strong indication as to what to expect from the Japanese luxury car brand, but he did suggest that the new model is needed. The current Lexus LS dates back to 2007, although it was facelifted in 2009 and again, more dramatically, in 2012.

“It is overdue, and I’ll admit that,” Templin said. “When Akio [Toyoda – head of Toyota Motor Corporation] asked me to come here four years ago, we created a plan, and that plan included a lot of different things and you can’t do them all at once.

“The first stage of that plan was to unify our design language, and we changed every one of our products in two years to have a new design language,” he said, referring to the refresh of the IS sedan and RX SUV among other key models.

“Then we started more emotional cars – more F Sport cars, more F performance cars [such as theRC F] coupe. Then some volume cars: NX has been a huge volume car for us that has grown our volume all over the world,” Templin claimed.

When asked if the LS replacement was not a priority for the brand – particularly in light of the fact that big sedans are falling out flavour with buyers while SUV sales boom – Templin said that wasn’t the case.

“It’s a huge priority, but LS is the most sophisticated car in our line-up, and you don’t want to bring a new LS to market until you’re ready for it,” Templin said, suggesting that there’s some big technological advancement for the new-generation car, which may not launch until 2017.

“So when we do bring the LS to market, you’ll see it will be a fantastic car,” he said.

“We don’t have any announcements to make about the next LS yet,” he said, before suggesting that the LF-FC (pictured below) and previous LF-LC concept models were “significant” and that those models offer a “real indication of where we’re taking the Lexus brand in the future”.

Templin went on to suggest that the new LS needs to move the game forward in terms of driving enjoyment. The current car is more about comfort than performance, not that that’s been a problem in the past given the buyer base.

But Templin made it clear that the buyer profile for Lexus is changing, and indeed the fact that cars like the Mercedes-Benz S-Class and BMW 7 Series have come before the new-generation LS means that the new big Lexus will need to be different.

“Flagship means different things in different markets,” Templin explained. “Here in Japan, flagship means you’re driven around and you sit in the back seat. All kinds of LSs and S-Classes and 7 Series driven here in Japan… That’s true of several markets around the world.

“A market like the US or Australia, people want to drive them, so they need to be fun to drive,” he said.

As for what may power the new model, that remains a mystery. Though it is clear that Lexus is moving towards offering more models with turbocharged engines, and that car could debut a new V8 engine with forced induction.

Templin had nothing to say about the potential for such an engine, simply adding “we will talk about that on another trip”.

Photochopper RM Design has created a rendering of next-generation Lexus LS using the LF-FC concept from the Tokyo Motor Show and elements of the new RX crossover.

The result is attractive enough, though it’s unlikely there will be any direct relationship between the LS and RX — the headlights may have strong similarities, I would expect the front grille more befitting of a flagship sedan.

What do you think?

Lexus has trademarked the LS 350 nameplate in Japan, suggesting that the next-generation flagship sedan may be offered with a V6 engine option for the very first time.

The 350 engine designation is the most common in the Lexus lineup, and likely means the LS will get some variation on the 2GR V6 engine that’s been used in the ES, RC, and everything else in between.

Prototypes of the next-generation LS have been spotted around the world, most recently in Death Valley, California for hot-weather testing. The new model introduction is rumored to be at the Detroit Auto Show in January.

(The LS 350 trademark is #2016069316, and was filed at the Japanese Trademark Office on June 27, 2016. Thanks Matt!)