From Concept to Car: Desert trials

Heat might not be what many of us think of as a problem (especially those in Northern Europe), but in sunnier climes it can make a car’s life incredibly difficult. An air temperature of 40 degrees centigrade might be uncomfortable for a human, but for metal-clad components it can be deeply unpleasant. And when they’re asked to, say, propel a car from 0-100kph in no time at all, or keep occupants cool, extreme heat can be a nightmare to deal with. 

There are few better places to put a car through its scorching paces than Dubai. The mercury there rides high all year round, making it the perfect place for Matt Clowes, Principal Engineer for Climate and Thermal Attributes at Polestar, and his team to put new cars to the test. 

In order to find out how a car and its componentry will withstand the heat, Clowes and co take them to two different environments. The first is almost a city… but not quite. “We start by going to a place called Half Desert. It's like a road network that was built with the assumption that they were going to build housing, retail, or something on there, but it never came to pass. As a result, you've basically just got an empty road network laid out like American blocks,” explains Clowes.

Half Desert allows the team to use the car, albeit to extremes, as a normal driver would. Tight turns, stopping, starting, low speeds, higher speeds, and all the types of driving you’d find in the real world, as well as some standing starts, repeat accelerations, and more, all with the sun beating down on the car.

Half Desert is only half the story though. To truly push a prototype to its limits you need to, well, push it. This is where the Jebel Jais mountain range comes into play. “Here we can simulate the kind of driving a customer might actually do. We could do some ‘enthusiastic’ driving, basically.”

While pushing a luxury GT to its absolute limits on one of the world’s great roads sounds like a blast, there’s actual work to do. Everything on the car needs to be measured to see how it reacts to the stresses it’s put through in high temperatures. Each fluctuation, temperature rise, and, well… everything is logged and measured. “In terms of measurement equipment,” explains Clowes, “There's loads on the car. There’s some in all of the thermal management system, which means all the temperatures in and out of all the various components, the motors, the battery, the inverters, the cabin, the HVAC system are all measured.” Coolant, refrigerant, and other components are monitored to assess their performance.

There’s a reason those areas are all closely looked at — they’re all cooled by the same thing. “It's a very holistic system. The same thing that cools the cabin, cools the battery, the motors… you get the idea. It's one big balancing act ensuring the systems that need cooling get it without degrading the performance of another too much.”

The car’s hardware and software are complex. Each has to know what the car is doing, where it’s doing it, and what conditions it’s under at any given time. On a European spring day, all will be fine and dandy, but in the heat of Dubai? The team needs to know how the software will cope. “Our software is developed in house, and it’s able to recognize different types of driving. We have what we call the driver index where it'll recognise you’re, say, driving normally, and the system prioritises cooling requests in a normal way,” Clowes continues. The system will change what it prioritises depending on what you’re doing. If it thinks you’re about to drive fast it’ll up the cooling on the batteries and motor, or if it thinks you’re hitting the track it’ll divert more resources to the bits that make you go fast and less to the cabin. 

To test this, Clowes and his crew do repeated hard acceleration tests. Sprinting from 0-100 kph over and over again sounds fun at first, but it can take its toll: “I’m fortunate,” says Clowes, “I’ve got quite a strong stomach. Some of the other engineers… maybe not so much. It’s quite brutal.” It’s repetitive, it’s unforgiving, and it’s fast, but it’s what the car needs to be able to do. Once the standing starts are done, they move on to 50-150 kph tests — not to simulate ‘enthusiastic’ driving, but more to test what’ll happen when you go for an overtake or join a motorway. Here, the system needs to sense that it’s getting a short, sharp, shock, and keep things as cool, calm, and collected as possible. 

It's hard and intensive work, even before factoring in the blazing heat. “We're still working with prototype vehicles. They're not production ready, so not everything works as it should,” says Clowes, “Just getting in and starting a car to test could take 10 or even 30 minutes if something's gone wrong with the software and you need to restart. Then you're sitting in a vehicle, and it's 50 or 60 degrees in the cabin whilst you're trying to get the software running.” And that’s only software. Hardware fixes mean the team may find themselves lying on the floor in the desert cursing their career choices. 

Thankfully, testing went well and the car is on track. But had anything gone awry Clowes and his team would have been on hand to figure out what went wrong, and why. Stress testing is important work — Polestar’s cars need to work in any situation, all over the world, and because of time spent in the desert, they can.