Proof-of-concept fuel-cell EV paves the way for BMW's entry into the world of hydrogen

In this business, it isn’t uncommon to come across new series-production cars that have been left conspicuously underdeveloped. But to find an experimental, proof-of-concept, never-for-selling machine that already feels very convincingly honed for public consumption? That’s quite unusual. 

Of course, no matter how plausible the BMW iX5 Hydrogen seems in isolation, there remains the not-so-small obstacle of how to refuel the thing. With its carbon-encased cylindrical tanks speedily brimmed with 6kg of hydrogen, compressed to 700bar and cooled to-40deg C, the iX5 will in theory go 313 miles before needing to stop. However, with few refuelling stations on the ground in Europe, stopping in just the right place is the tricky bit.

You might be surprised to hear that the iX5 is fitted with a conventional turbocharger and intercooler. They're needed to achieve adequate power from the fuel-cell stack.

Everything you need to know about hydrogen cars

BMW suspects that as heavy industry turns towards hydrogen and ICE options are legislated into the margins, a robust hydrogen refuelling network will germinate, such that using it for certain cars will in time become a no-brainer. 

Bmw ix5 hydrogen review 2023 04 front tracking

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But that’s all hypothetical. For now, BMW’s goal is to be ready – readier than rivals, at least – for such an eventuality arising, and this is why the iX5 exists, albeit at a tiny scale.

Rather than being built en masse alongside every other X5 derivative at BMW’s vast SUV plant in South Carolina, the US, this hydrogen fuel-cell version is being hand-assembled in Munich, Germany, with fewer than 100 examples to be made.

They will form a pilot fleet not unlike those of the old Mini E and the 1 Series-based ActiveE field-testing models that were put into the hands of select members of the public around 10 years ago. Those cars paved the way for the genuinely ground-breaking i3, which in turn empowered BMW to launch the i4, the iX, the iX1 and now even the i7. It would take years, but the iX5 could one day prove to have played a similar, acorn-like role for future FCEVs, which BMW executives insist will be offered alongside, rather than instead of, the BEVs that have rapidly established themselves.

Our iX5 test route in and around Antwerp in Belgium was revealing insofar as it revealed absolutely nothing untoward about the fuel-cell driving experience. To all intents and purposes, this prototypical X5 feels much like a more conventional battery-electric iX5 might, and that’s down to the power delivery.

As with existing FCEV efforts, such as the Hyundai Nexo and Toyota Mirai, hydrogen is fed from those carbon-clad tanks and into a fuel-cell system (incidentally, the cells are supplied by Toyota) that separates H2 molecules into protons and electrons. The electrons form the current that powers the drive motor, while the protons combine with oxygen ingested from the atmosphere to create the car’s only exhaust product, water. The point here is that the motor is the one you will find on the back axle of the battery-electric iX xDrive50, and it behaves in exactly the same way, being smooth and responsive. Note also that the car’s rear-mounted motor is its only motor, making this the first purely rear-driven X5.

As ever, things aren’t quite that simple, at least concerning the powertrain. The fuel cell itself is capable of supplying enough draw only for about 170bhp. The rest comes courtesy of a small, high-performance lithium ion battery pack that sits just beneath the boot floor. This is constantly being topped up by electricity from the fuel cell, and when you really put your foot down, it's responsible for supplying not only that instant-feeling acceleration pick-up (if drive was delivered directly from the fuel cell, there would an ever-so-slight delay) but also the additional shove needed to see the iX5 realise its full potential of 396bhp and 524lb ft 

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These surprisingly serious figures make BMW’s effort the most powerful homologated FCEV ever. However, they’re also up against 2460kg, so roll-on acceleration is more reassuringly swift than outright exciting. 

Traffic was abundant, but it gave us a chance to cast an eye over the car’s interior. Not that this took long. It’s traditional X5 in here, only with blue detailing, the likes of which we’ve seen on BMW’s BEV offerings (FCEVs will exist under the same i sub-brand). There’s a percentage readout for remaining fuel and an economy readout in KG of H2per100km, all neatly integrated.

For the record, during an easy-going two-hour drive, our car used 1.6kg of H2 per 100km, which translates to 233 miles on a full tank.   

Out of town, the handling proves composed, the car nicely balanced. The steering is also refreshingly honest, perhaps because BMW hasn’t just deactivated the donor X5’s front driveshafts for this FCEV application but shelved them entirely. The fuel-cell stack itself – housed in aluminium but hidden under a slab of matt carbonfibre – is also interesting in that its dimensions and weight are a close match to that of a four-cylinder turbo engine. It means the iX5 doesn’t morph into some gangly, nose-heavy monstrosity at the first sight of a decent corner. It’s quietly satisfying to flow along, much like any X5.

These cars also have air suspension all-round, and an engineer told me the weight distribution is almost perfectly equally distributed – an unintentional but encouraging finding that, not to get ahead of ourselves, bodes well for any fast FCEV saloons that may surface in the dim and distant future. For now, the only concession to driver-appeal is a Sport driving mode, which sharpens powertrain response. Note, however, that there's little to no shape at all in the power delivery. It’s all quite staid.    

Bmw ix5 hydrogen review 2023 13 cabin

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As for noise, this could easily be a BEV iX5 but for your occasional awareness of a very faint hum from the powertrain, most noticeable while waiting at traffic lights. On the move, the iX5 is superbly refined, even at higher speeds. Luggage space is unsurprisingly inhibited by the elements of the powertrain that sit beneath the boot floor, but that floor is exactly the same height as that of the X5 xDrive45e plug-in hybrid, so still acceptably low.

Then there are the hard advantages that any FCEV would bring over any BEV: no range reduction in cold weather and the ability to fully replenish its long range (313 miles here) in just four minutes. Mind you, at this point I feel duty-bound to point out that an X5 xDrive40d diesel, although 61bhp leaner, is every bit as quick to 62mph and will keep going for 680 miles.

The comparison in all-out range with ICE cars is rather a moot point, though. The iX5 has spent four years in development but won’t ever go on sale because the external ingredients for success aren’t yet in place. If such a BMW does ever become available at your nearest dealership, it will be because hydrogen refuelling stations have become omnipresent, at which point the difference between 313 miles and 680 miles would be academic in light of the short fuelling time. But who knows when that might be? BMW reckons the second half of the decade at the earliest. 

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But let’s imagine that we are in fact already living in 2028 – or just today in Japan, with its 161 hydrogen stations and ambitions to have 1000. The iX5 would slot pretty seamlessly into BMW’s line-up as a credible contender against both ICE and BEV rivals, blending their strongest attributes but with neither technology’s major drawbacks.

True, it’s a bit soulless and surely wouldn't be cheap, but the iX5 is clean at the point of use, fast and refined on the move and quick to refuel. Then there’s the fact that, during build, an FCEV requires but a small fraction of the so-called ‘critical raw materials’ that an equivalent BEV eats up. And even then, the platinum that one fuel-cell stack needs could be scavenged by recycling the catalytic converters of two retired ICE cars. 

Fuelling infrastructure aside, add everything up here and you have a solid case for this FCEV by BMW, which serves only to make its current liminal existence seem all the more strange. The last time its maker put this kind of graft and finesse into something with no imminent payoff was the Group 5 M1, and that was accidental. Equally, what the technology inside the experimental iX5 Hydrogen has in spades is the one thing of which that old racer simply couldn't get enough: time.  

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Richard Lane

Richard Lane
Title: Deputy road test editor

Richard joined Autocar in 2017, arriving from Evo magazine, and is typically found either behind a keyboard or steering wheel.

As deputy road test editor he delivers in-depth road tests, performance benchmarking and supercar lap-times, plus feature-length comparison stories between rival cars. He can also be found on Autocar's YouTube channel

Mostly interested in how cars feel on the road – the sensations and emotions they can evoke – Richard drives around 150 newly launched makes and models every year, and focuses mainly on the more driver-orientated products, as is tradition at Autocar. His job is then to put the reader firmly in the driver's seat. 

Away from work, but remaining on the subject of cars, Richard owns an eight-valve Integrale, loves watching sportscar racing, and holds a post-grad in transport engineering.