The World’s Most Efficient Car: Musk Should Be Worried About Mercedes

Source: Medium, Will Lockett
Photo: Mercedes EQXX — Mercedes

The EV revolution is now in full swing. Currently, every manufacturer on Earth is scrambling to get a slice of this electrified pie. But despite the billions spent on development, none of these established automakers have come close to Tesla’s prowess. That may be about to change. A few months ago, Mercedes showcased their EQXX prototype to demonstrate how they will take the fight to Musk and become a major player in the EV world. Well, this prototype recently drove 747 miles (1,202 km) on a single charge and broke the EV range record! So how did they achieve this astonishing feat? Can this technology find its way into a mass-market car? And how concerned should Musk be about Mercedes’ new development?

Mercedes didn’t just strap a massive battery to a car to get this monstrous range. What would be the point in that? Instead, they focused on three things: powertrain efficiency, aerodynamics, and weight, to create an ultra-efficient vehicle. The solutions they devised to eke out every last mile of range are truly astonishing.

Firstly, the powertrain efficiency. This refers to the battery, inverters, cabling, motors, driveshafts, and wheels. Each one of these components has inherent ‘losses’ and reduces the overall efficiency of the car. Take, for example, a Tesla Model S. You can charge it up with 100 kWh of energy, but when driving, some of this energy will be turned into heat in the batteries, cables, and inverters, or lost to friction in the motors, driveshafts, and rolling resistance of the wheels. When the Model S first came out, its overall “drivetrain efficiency” was at 80%, but it has been refined over the years to an astonishing 90%. This means that a new Model S can use only 90 kWh worth of energy to actually push it down the road.

But the EQXX takes things to another level of efficiency here. Firstly, the battery is a normal 100 kWh lithium-ion unit, but it uses silicon anodes rather than the typical graphite. Silicon can hold waymore lithium-ions than graphite and produces far less heat during charging and discharging, increasing its efficiency. It is also far more energy-dense, which is why the pack weighs 30% less and is 50% smaller than anything else Mercedes has developed. The reduced heat levels mean the battery doesn’t need intense liquid cooling like the Tesla, which requires a lot of energy to run and weighs rather a lot. Instead, it can get away with less powerful, lighter air cooling and save energy.

The same is true for the motors, which are permanent magnet motors. This is the most efficient type of electric motor, but Mercedes has tinkered with it and used tech from their F1 team so that these motors produce far less heat than usual. Again, this makes it more efficient and means it can save energy and weight by using air cooling rather than liquid cooling.

These components allow the EQXX to achieve an astonishing 95% drivetrain efficiency. This may only sound like a small jump from the Tesla, but a drivetrain efficiency increase of 8% will typically extend the range by 15%. So overall, this is a significant leap forward.

Then we come to the aerodynamics. At first glance, you can clearly see the lengths that Mercedes has gone to. The teardrop shape, flat covered wheels, minimal panel gaps, and race-car-inspired diffuser make the car look like it could cut through the air with minimal effort. But these changes are more than just skin-deep.

Take the virtual wheel covers. Wheels are a nightmare for aerodynamics. They mess up the airflow and create heaps of power-draining turbulence. One solution is to cover them with a body panel, but then you create issues during snowy conditions, as the snow accumulates in the wheel well and stops the car from steering. So instead, Mercedes channels an air curtain around each wheel that acts as a virtual wheel cove which smooths airflow and massively reduces drag. However, this isn’t the only aero trick on the car. The diffuser (an aerodynamic device in the rear bumper) is designed to allow the airflow underneath and above the car to rejoin smoothly, which reduces turbulence and drag. But given the fluid properties of air change, it needs to be a different size for low airspeed and high airspeed. To solve this, the EQXX’s diffuser extends at 37 mph to keep the car optimal.

All of this combined means that the car’s drag coefficient is a tiny 0.17. That makes it 30% more aerodynamic than a Tesla Model S! (Which is one of the most aerodynamic cars ever produced.)

Finally, we have the weight. We already know that the battery and motors are very light and compact as they don’t need a heavy liquid cooling system. But this also means that the car can be built smaller and lighter too, as packaging can be optimised. This is why the EQXX only weighs about 1,700 kg, despite having a sizable 100 kWh battery. As the car weighs so little, it needs less power to accelerate, which in turn extends its range.

All of these aspects allow the EQXX to travel 747 miles on a single charge, whereas a Tesla Model S Long-Range struggles to get over 400 (WLTP range of 405) with the same sized battery. That makes the EQXX a mind-blowing 84% more efficient!

But this is only a prototype vehicle. It isn’t going into production. So it doesn’t really threaten Tesla? Right?

Well, actually, it does.

To begin, Mercedes Technology Officer Markus Schäfer told Top Gear magazine that “something resembling this will be put into production.”Furthermore, most prototype vehicles are not fully developed. They rattle and aren’t refined properly, as it would cost far too much to develop a non-production car to that level. But when Top Gear tested the EQXX, they found it to be at a near-production level of development and refinement. So it seems that Mercedes is spending the money to make this as production-ready as possible.

But it might not matter if the EQXX doesn’t make it into production. Every aspect of the car can be either retro-fitted into their current lineup of EVs or easily implemented into their next generation. Take the silicon anode batteries. Right now, they are damn expensive, but once manufactured at scale, they have the potential to be on a cost parity to ordinary lithium-ion batteries.

So a production EQXX, a massive range EQS (Mercedes equivalent to the Model S), or a low-cost EQC (Mercedes equivalent to the Model 3) could be on the way soon. That should deeply worry Tesla, as this could take a sizable portion of its market share.

But there is one final aspect of the EQXX that is worth mentioning. The battery makes up about 30% of an EV’s cost, and in the real world, most people only need a range of around 250 miles. So Mercedes could use this tech to make a super affordable car that can manage to do 250 miles from a 33 kWh battery. The smaller battery could make it thousands of dollars cheaper than anything else in that range, and would also mean it could charge quicker as there is simply less battery to charge!

If Mercedes can pull off such a car , they won’t just threaten Tesla. They could become the dominant player in the EV market!

So if I were Musk, I would be worried. Mercedes is rapidly catching up, and potentially overtaking Tesla in terms of efficiency and range, which has been Tesla’s biggest selling point. Without that market lead, the only other way Teslas are better than other cars is their self-driving capability, but Mercedes is already hot on their heels there too. So, could we soon see the king of EVs dethroned? Quite possibly.

https://medium.com/predict/the-worlds-most-efficient-car-musk-should-be-worried-about-mercedes