Why electric racing cars should be four-wheel drive

I’ve had the opportunity to drive many iconic cars with Audi, and getting to try the S1 Quattro recently was particularly special. That was the car I played with on my sofa as a little kid – the S1 was born the same year I was in 1984. This was a period when the Quattro four-wheel-drive system became very famous on road cars, having been proven with great success on the rally stages.

It was an interesting opportunity to compare against the new electric RS e-Tron GT to demonstrate the differences between a combustion engine and an electric motor with Quattro capacity.

In the S1, I had several runs up the hill in San Romolo with the 1984 WRC champion Stig Blomqvist sitting next to me. He told me that he used to drive front-wheel-drive cars in his early days, and when he first drove the Audi Quattro it was a big step forward in terms of traction.

The first thought you have when you’re about to drive the S1 is that it will be everything you dreamed of as a little kid and more. But the reality is that technology has evolved so much over the past 40 years that, by contrast with modern cars, the S1 is extremely difficult to drive.

I didn’t push the car anywhere near its limits, but that wasn’t necessary to understand what it would have been like for Stig, Hannu Mikkola and Michele Mouton on the rally stages. For example, the S1 has an H-pattern gearbox so it takes time to shift up or down, and the turbocharged engine has a very narrow rpm band. If you don’t get it exactly right through a low-speed corner, the car feels like it just stops.

You had to heel-and-toe to change gear, and at the same time you needed to keep the throttle pressed to maintain the turbo pressure. Stig was braking with the left and with the right foot pretty much in every corner, which was very impressive to watch. But you need years of experience to master that technique. It was clear to me how today, not only are the cars much faster but they are also generally much easier on the driver.

Di Grassi found the S1 tricky to drive in demo runs and marvelled at Blomqvist's technique

Photo by: Audi Sport

This is the case whether you have a four-wheel-drive system or not – it’s mostly down to modern electronic controls that determine how easy cars are to drive.

I’ve heard a lot from the FIA that four-wheel-drive cars are easier to drive than a FWD or RWD, like the Gen-2 Formula E car or the Audi R8 LMS GT3 I’ve been racing in the DTM, but that’s not the case at all. It’s just a different technique that has its own challenges.

For example, in my last year of LMP1 with Audi in 2016, we had around 500 horsepower on the front axle from the electric motor and 500 horsepower on the rear axle from the turbodiesel combustion engine, with a huge lag. Whenever you touched the throttle coming out of a hairpin that involved accelerating and turning, like the Turns 2-3-4 complex at the Shanghai International Circuit, the front axle wanted to instantly give the power while the engine was charging the turbo at the rear, which meant the car would understeer and then oversteer as the control systems tried to distribute all that horsepower. As a driver, you had to be on the right line and use the throttle in the right way to maximise the slip angle and ensure the car had enough longitudinal potential.

Most electric sportscars follow a four-wheel-drive philosophy because you can have so much regenerative braking from the front axle. The way weight distribution works means that when you brake, you have more capacity at the front

Away from the rally stages, the limited use of four-wheel drive in top-level circuit racing today is a factor of regulations rather than technology. When regulations don’t constrain technology, naturally the cars will go in that direction if there is the budget and the knowhow to make it work. We saw that this year at Le Mans, with Toyota winning the Hypercar class over the two-wheel-drive Glickenhaus.

Famously, four-wheel drive was a failure in Formula 1 in the 1960s, with Colin Chapman forced to abandon development of the Lotus 63. But if it was allowed today, you would expect F1 teams to use it because four-wheel drive allows you to optimise the capacity of the tyre in every direction – acceleration, cornering and braking. It’s the same story with Formula E, where I believe it’s a no-brainer to adopt four-wheel drive.

Most electric sportscars follow this philosophy – the RS e-Tron GT has one motor on the front and rear axles, and no mechanical connection between the two axles – because you can have so much regenerative braking from the front axle. The way weight distribution works means that when you brake, you have more capacity at the front.

Di Grassi believes four-wheel-drive in Formula E would provide power, re-gen and weight benefits

Photo by: Sam Bloxham / Motorsport Images

The weight added from putting an electric motor at the front of the Gen-3 Formula E car could be offset by removing weight from the battery capacity, which you could do because of the extra recuperation given by the front axle. You would gain power with the same range, and use much less of the mechanical brakes because the energy recuperated under braking would also be increased. If it can be done in a cost-effective way with a fixed torque distribution, there is basically no downside.

The question then concerns what set-up is best for a four-wheel-drive configuration. Do you do it with a single engine and a mechanical diff, two motors on the front and rear axle, or one independently powering each wheel? Depending on how much torque each motor has, and if you can break the traction limit upon acceleration, the optimum solution is having a single electric motor connected to each wheel that allows for full torque vectoring on the car.

If you add to this all-wheel steering, so each wheel is steering and accelerating independently, then you have the optimised solution for any car. That’s the holy grail of racecar engineering where you cannot do anything more to maximise the tyre contact patch and no compromise is needed.

This is impossible to do with combustion engines because you always have a mechanical device distributing the torque. With the electric motor, that’s not the case because you can have each independent motor working at millisecond frequency to change the torque powering each wheel.

But this brings other questions. How much assistance is too much? One of the discussions we have had at Roborace concerns the level of assistance that a driver should have when comparing their performance against a fully autonomous algorithm-driven car. Where an AI car can be set up so that each wheel is controlled independently at any given point, even the most skilled human driver can’t possibly do that.

So when judging the capability of the human, do you allow the computer to distribute the torque on top of your driving skills, or should it be all about the inputs given to the car by the driver, as it was with the S1?

If you say that the human and the autonomous driver should be considered totally separate, that the human can only control what they are capable of and the computer can control pretty much everything, then the computer is already faster than the human by far. But if you allow the human to be in partnership with a computer, they are still faster than the computer alone for the time being. 

Possibilities for four-wheel drive are almost limitless and its full potential is still being explored

Photo by: Audi Sport

The possibilities for four-wheel drive are only just beginning to be fully explored and can go in all sorts of avenues in the future. As I’ve said before, I think there is value in pushing the limits of technology for autonomous vehicles, but this doesn’t have to be at the expense of traditional motorsport with gladiators behind the wheel who fans follow and admire. They can exist alongside each other as two semi-separate spheres.

If more series organisers decide to allow four-wheel-drive cars, but with a fixed torque distribution to still have this human input into the car as much as possible, then it won’t detract from the spectacle for fans, even if you would likely see much more V-shape cornering than with only RWD because the front tyres would be optimised for acceleration.

There are companies out there that specialise in retrofitting classic cars with the latest technologies to make them more efficient. But should we do this with the S1? For me, the right approach is to keep the cars that we dreamed of as kids the way they are, with the sound they have – the S1 is just amazing when you change gear – and bring the new technology with the new cars.

Updating classic machines is currently in vogue, but Di Grassi advocates keeping them in their original spec

Photo by: Audi Sport