We've said this for a while now: Lexus is on a roll. LF-LC, LF-CC, LFA, IS and RC are all pretty stunning (if you'll ignore their boring acronym names).

Next up on the roster of updates, and adopting the L-Finesse design language is the LS flagship sedan, is the LF-FC (“Lexus Future Fuel Cell”) – a concept car (for now) that challenges the Merc S-Class and BMW 7-Series.

In our reviews, we've often suggested that if you're bored of the German default you should really try out something from Japan. And having seen the LF-FC unveiled at the Tokyo Motor Show, it's easy to see the appeal.

We'll come to the powertrain tech in a minute, but first up let's talk exterior design. If you're doing a massive saloon, likely to be driven by the world's CEOs and captains of industry (well, maybe they won't be driving), the rules suggest that you need to be sober and sombre in style.

Cars like the BMW 7-Series and Mercedes S-Class are reasonably elegant, but rather generic and big sedans. They certainly don't shout. But no one's told Lexus. So the LF-LC suggests Lexus has every intention of following its push-the-boat-out design language for the new LS, as and when it arrives.

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What that means is that the LF-FC we've seen has the biggest version of the company's “spindle” grille yet (it's massive but looks brilliant), along with the most dramatic interpretation of those Nike ticks (sorry, Lexus lights) yet.

Look at the lights close-up, and from above the tick shapes actually form a bridge where the front wings detach from the body side. It's all very dramatic, and all in the name of aerodynamics. So if you want bold style, the next big Lexus looks likely to be up your street.

At the back too, some of the most imposing rear lights we've ever seen define the corners of a car are dripping in shiny chrome edges. No demure, delicate BMW light pipe here. You get light pipes with Lexus – just about 10 of them.

Unfortunately, what you don't see in our photos (click the full gallery above to make the most) is that in getting all excited about the crazy details, grille and lights madness, Lexus forgot a few car design basics: the wings attached to the form that sweeps off the grille don't really work, as they crest too far back; and the body side surface kinks up awkwardly ahead of the rear wheel – reminding us of the Toyota Mirai.

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Oh, and the LF-FC's C-pillar is too stuck out. The upper cabin of the car never tucks in, so it all looks a bit stiff and ungainly from some angles. Yes – we know you'll be saying “I don't care about the minutiae of car design” – but if you're going to buy a car like this you want it to be spot on, immaculate and elegant; a representation of you and your business.

What does look particularly stunning, though, is the interior. With opulent chairs, quilted leather a-go-go, layers of thin, matte-finish wood and a digital display that runs across the full dashboard of the car, defining a new cockpit architecture. This is apparently touchless – it's controlled by gestures – but we weren't able to actually get inside the LF-FC to have a proper play. So we can't truly tell you what it did or what it was like as we couldn't poke our cameras – let alone our heads – inside. Shame, as this hints at being the best Lexus interior yet.

The observant among you will have clocked that the FC name stands for Fuel Cell, marking a bit of a departure for Lexus – a company that has become an entirely hybrid brand in the UK. So will the next LS be propelled by a hydrogen fuel-cell? The reality is, Lexus's hybrid petrol-electric technology is better developed and matured right now that anyone's. And in the wake of Volkswagen Dieselgate, hybrid will make sense and appeal to a lot buyers.

So we wouldn't expect the hydrogen bit of the technology to make a mainstream appearance in the next LS for now. Mother brand Toyota clearly believes that the stuff is the long-term future – the Mirai is evidence of its commitment to the technology and the Japanese government is heavily incentivising and pushing its car markers towards the stuff. But in Europe the infrastructure is years away and hydrogen fuel cell stacks are still expensive.

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With EV battery re-charging times set to be cut rapidly in the next few years, we can't see hydrogen going big in the near future. So expect the LF-FC, when it matures into a production, to remain a petrol-electric hybrid. Expect it to be the most autonomous-enabled Lexus yet, too – the LF-FC has an “elevated level of traffic environment recognition” according the Lexus. It predicts what others are going to do before you do, and should be able to all but eliminate accidents.

Ultimately, for all these ifs and buts, it's hard not to admire the LF-FC and what it might represent about Lexus's future. Right now, the brand seems to be the only one that's genuinely taking the fight to BMW, Mercedes and Audi in terms of premium appeal, stand-out design and cutting-edge technology.

As seems to be the way with Japanese car brands, we believe the LF-FC to be a showcase of a work in progress. Here's hoping that when we get to the production LS, the design will be a little more refined and, who knows, Lexus will make us eat our words and have the fuel cell technology ready for prime time, too.