BMW 5 Series GT FCEV 2015 Review

What do most people say when you ask them about electric cars? Most say they are quiet and strong around town, they zip around cities superbly and then the batteries suddenly die like an iPhone, leaving you stranded in peak-hour, blocking the busiest lane, with people honking and yelling at you.

Well, there will soon be a way you can have the first part of that without the second.

Toyota might already have its Mirai on sale, making it the first car to hit showrooms with hydrogen fuel-cell power, but BMW isn’t sure that small city-cars are the way to go as it plans to join the party in 2020.

That’s why it is letting us drive two of its fuel-cell electric prototypes at its Miramas test track, and that’s why both of them have all the technology stuffed into the bodyshells of the 5 Series GT.

It’s BMW’s belief that the future will see battery-electric vehicle (BEVs) used for small cars and city work, while plug-in and range-extender hybrids will be used for mid-range work and hydrogen fuel-cell electric cars (FCEVs) for longer distance driving.

“A fuel-cell vehicle is going to be used for long driving,” BMW’s vice-president of powertrain research, Matthias Klietz insisted.

“That’s why we have categorised it as a large vehicle, because it will work best if it’s doing more than 18,000km a year.”

In BMW-speak, that means hydrogen fuel-cells should be inside bigger cars and there's probably another full generation of system development before it builds one you can buy.

“We have done a lot in the past years without presenting this information to you,” BMW’s board member for development, Klaus Fröhlich, said.

“In the past we were asked in interviews what we were doing and were we late in our development, but you don’t always put your development into production and we have been working with fuel-cells for 30 years.

“These are research cars and they are supposed to show you how far we are with the vehicle development. It’s not just about driving fun but about how far we are with innovations and interest for the customer in the future at an appropriate price level.”

And what the 5 Series GT fuel-cell delivers for absolutely no customers whatsoever is 150kW of power, a 0-100km/h sprint of 8.4 seconds and a 180km/h top speed.

And there are two of them. One of them is the (only comparatively) yester-tech version with a 700 bar hydrogen gas tank inserted down its length, while the other is a latest generation system with a cryogenic tank that holds liquid hydrogen. They both look like torpedo tubes.

The big difference is not weight, surprisingly, but that the old-school system holds 4.5kg of hydrogen, while the new-school cold tank, with an internal pressure of just 350 bar, can hold 7.1kg. Effectively, it almost doubles the 450km range of the 'standard' one, pushing it out to 700km.

Other than that, both cars have identical electric motors driving the rear wheels and identical two-speed transmissions as well. Apart from adding spring stiffness to cope with the extra weight, the chassis, suspension, braking and steering systems are carried over from the standard 5 Series GT.

Of course, that leaves the question of infrastructure, which BMW has also been working on, especially since the 2006 Hydrogen 7 Series convinced it that chilled, liquefied hydrogen was the way forward.

“One petrol fuel station pump can supply about 100,000km of energy a day,” Klietz said. He knows. He and his team sat at petrol stations around Munich and documented the fuel volumes each pump delivered, then compared them to NEDC figures.

“With hydrogen at 700 bar, we can already cover 50 per cent of that, but cryogenic hydrogen storage will give us similar volumes to the petrol stations.”

Given that a hydrogen fuel-cell car is essentially an electric car that uses the hydrogen to masquerade as a bigger, on-demand battery, its behaviour is unsurprisingly similar to a battery-electric car.

There is no difference inside the 5 Series GT’s cabin, either. There’s nothing much to get used to, except for the chunks of luggage capacity the power electronics soak up in the boot area.

You start it by pushing the 'On' button, pull Drive on the standard BMW automatic gear lever and then you’re just driving a two-pedal car.

It’s immediately and demonstrably heavier than the standard version of this car, and Klietz admits it would easily be more than 100kg overweight – which isn’t a massive surprise for an early prototype that hasn’t been trimmed down for production.

“Each single component and the tank itself are heavier than they would be in production, but it’s a prototype and we have to make the system work first,” Klietz said.

But it still drives smoothly and briskly, if not quickly. Audi’s A7 h-tron has more power than this (170kW versus 150) and had crisper throttle response, especially at low rpm, but it’s not bad.

And the pursuit of power isn’t really the point. After all, to get more power, you just make a bigger stack.

“It could be faster, but the output can be regulated by the number of cells you put in it. We are looking at a range of 200 to 400 cell-stacks, depending on the power you want to achieve,” Klietz explained.

The fuel stack itself comes from BMW’s fuel-cell technical partner, Toyota. BMW contributed the fuel stack’s housing, the high-voltage battery and the hydrogen tanks, and it shared the load on the auxiliary systems.

For the uninitiated, a push on the accelerator pedal tells the fuel-cell stack to force hydrogen from the tank onto an anode plate, where each hydrogen atom is broken into protons and electrons. The protons migrate through polymer cell membranes to reach the positively charged cathode at the other end.

There they react with oxygen (fan-forced from the atmosphere into the stack), creating water vapour. The separated electrons, meanwhile, supply the car’s electricity.

It’s not as quiet as you’d expect, though. There are cooling fans for the battery and the fuel stack, plus fans to force air into the stack to speed up the electricity-generating process. They’re not hugely intrusive, but they’re surprisingly noticeable.

The overwhelming impression at town speeds is that it moves about as well as the standard one with a four-cylinder petrol motor, but has more effortless urge at light throttle openings and at low speed.

The ride is firm and yet it still wallows as it deals with bumps and corners, though that’s far from the point. BMW claims 8.4 seconds for the sprint to 100km/h, but it took about 10 seconds when we tried it with three people on board on a very hot day after the car had been driven for hours.

The reality is that while a good petrol engine is about 36 per cent efficient, a fresh fuel-cell is 65 per cent efficient, but that can drop to 45 per cent when it’s hot (with heat and the compressor fan taking almost all of the losses). But it remains a lot more efficient, and its emissions are still just heat and water vapour.

And there’s another surprise. Where Audi’s A7 h-tron uses a single gear, the 5 Series GT has a two-speed, hydraulic automatic transmission.

It changes up to the taller gear at around 90km/h when it’s on full throttle and Klietz says it’s there to let the car work properly at both town and highway speeds in the meat of its best performance.

It’s a set-up that works better than the Audi system, and it lets you cruise comfortably and quietly at all speeds, without sacrificing throttle response.

You can stand on the throttle at 110km/h and expect it to surge forward, with a little gear whine. You can do the same at 30km/h and expect it to do the same, with more urgency.

It also punches out of corners well, taking advantage of all that early, instantly responding torque, which tapers off with speed.

In fact, the gear whine from the prototype transmission is more intrusive than any noise coming from the fuel stack or the electric motor, though BMW doesn’t see this as being remotely insurmountable in production.

It’s an easily driveable machine, even in its prototype stage, and feels well formed. You could easily carry five people in it, comfortably, though it could use more power if you decided to plonk it as-is onto real roads.
But we’ve got plenty of time before BMW does that…