Ariel is best known for its lightweight, petrol-powered track- and performance-oriented cars. The company's iconic Atom, for example, is a featherweight road racer with two seats, no roof, and no doors. 

However, the company has recently revealed the HIPERCAR. Unlike its other efforts, the HIPERCAR has a roof and two doors and — most significantly — four electric motors.

The powertrain for the car, including a unique gas turbine range extender, was supplied by Cosworth. Auto Futures spoke to Simon Dowson, a Managing Director at the company to find out how the two collaborated on making the staggeringly quick and head-turning HIPERCAR go like the clappers.

"When the project was first conceived back in 2017, there were very few 800-volt architectures out there in terms of high-performance battery systems. So it was about delivering an 800-volt pack that would give the performance that met with Ariel's requirements," explains Dowson.

Those requirements, when presented on paper, make for some reading. The HIPERCAR car hit 60 mph from a standstill in 2.09 seconds, while 100 mph can be reached in under five. 60-120 mph happens in just 3.5 seconds. The top speed is 155 mph.

However, while 0-60 times are, in Dowson's words "meaningless," the most unique thing about the HIPERCAR is its gas turbine range extender — the CAT GEN.

"We've been building it for a number of years as an onboard charging device," explains Dowson.

"We're excited to have that as something a bit different, rather than just a standard battery-electric vehicle. But in particular, this type of application where you're going to do some fairly, potentially some fairly aggressive track-based driving, and you're not sure what charging infrastructure is going to be available to you, you've then got the option to have something that is there to charge the battery and get you home for your multiple standard duty cycles on road."

The CAT GEN truly makes the HIPERCAR stand out from other fast electric machinery.

"As a system, you basically have a high-speed electric motor on one end of the system," Dowson explains.

"That has a shaft that runs through it with a rotor on in with magnets. That same shaft is the coupling through the compressor wheel and the turbine wheel. So, you are drawing air in like a turbocharger. It flows the cool air coming into the compressor wheel, which is then pinning the wheel around. That air is then going from the outlet of the compressor side, through a heat exchanger and gets pre-warmed to about 300 degrees. You're then injecting fuel and you're putting it into a catalyst at which point you're going to get a reaction within the catalyst to create a hot gas."

That hot gas is then sent over to the turbine side before heading out the exhaust. The spinning shaft, which can hit 110,000 RPM, generates electricity and sends it back to the battery. It's a serious piece of tech.

"The basis of the turbine system was having it as a standalone that doesn't need additional cooling," says Dowson.

"There's no oil feed to the bearings, there's no coolant for the bearings. It is a standalone unit."

However, the CAT GEN system was not created specifically at the behest of Ariel. 

"When we started developing the range extender, it was around automotive applications and this was a way of demonstrating it in a more performance environment," says Dowson.

"Now the range of most electric cars is pretty good, especially the ones coming out now and you're getting a 250-mile range, they're probably going to see you okay. But people always think about 'What happens when I want to go further?' or 'Someone's on the charger, or the charger isn't there, and what if it's broken?' So, our range extender satisfies some of those concerns. 

"But now, a lot of our applications are in different sectors where maybe a larger commercial vehicle is required and you don't have a huge battery. We demonstrated it last year at LCV [Cenex] in a Ford Transit. We took out the one-litre engine and put in the CAT GEN. We increased the battery size to give it a range of 90 miles, rather than 30, and it was 60 kilos lighter than the original vehicle."

Dowson also explains that Cosworth has deployed the CAT GEN system in sailboats, in defence applications, on building sites instead of diesel generators, and in road-side assistance applications to help stranded drivers with flat batteries. 

"COVID was a significant implication. It stalled the project for over a year because Ariel couldn't perform its standard business," says Dowson.

"It basically had to stop trading for a year which had some serious knock-ons to the program. We carried on and were able to continue developing the technology but then getting that through to the vehicle integration was reliant on Ariel."

Working in that environment would have been challenging for the companies but, Dowson explains that, as Ariel was used to buying "off-the-shelf" components, there was some wrangling to get the car up to spec.

"It was good [working with Ariel] but I think the biggest challenge we had in working together was them being able to describe what they wanted in terms of power delivery for the vehicle.

"They could only refer back to 'If it has a fixed diff, it wants to feel like this' or 'We've got something and it feels like this.' We were saying, 'It's not like any of those.' We were trying to disseminate their requirements in terms of track-based performance using their current platform, so using a Nomad or an Atom as a benchmark, rather than an EV platform, which obviously tends to drive slightly differently."

However, HIPERCAR's long gestation process did reap some rewards.

"With OEMs, you've got to find a compromise between the system, the system layout, the thermal behaviour, the performance requirements, and the vehicle's styling," says Dowson.

"In this instance, the battery is the size of the chassis. We went through a couple of iterations in order to be able to have the cell technology developed. We actually changed cell supplier during the program so we were then able to reduce the height of certain things within the pack and that knocked-on to the chassis to give them a little more space. It was always that sort of two-way between us as a supplier to the vehicle and then the vehicle manufacturer."

"Most people know Cosworth from the internal combustion engine side of things but, naturally, you would also think about performance and agility and speed to market which is ideally suited to the changing environment," says Dowson.

Dowson thinks that the current uncertainty about the future production and use of energy stands to benefit the company.

"There's a lot of hype about hydrogen at the moment and it reminds me of when we were involved in electrification really early," he says.

"We built our first [electric] car in 2009 and there was only really the Tesla Roadster around at that point. Hydrogen reminds me very much of early electrification, there's a lot of enthusiasm towards it and positive news but when's that actually going to happen? And, from a safety perspective, you can't really deal with a big hydrogen leak."

For Dowson, an easier solution would likely be in renewable materials and in biofuels.

"How we can repurpose waste materials and capture gases and things like that are really playing into future propulsion," he says.

"I think we're going to start running into issues with materials that go into batteries and the mining and all of those things. We've seen a big swing towards battery-electric, but I think we're going to come back a little bit from some of that, and look to potential downsizing and alternatives, whether it's through some form of combustion or things such as the CAT GEN to be able to deliver power to top-up but using energy sources that are recovered from other waste materials, potentially."

Fortunately, with Cosworth's ability to chop and change and adapt to changing circumstances, it seems that the company is in good shape for whatever the future holds.