As carmakers continue to seek out a competitive edge, one area that can significantly enhance EV performance is aerodynamic optimization. We've found that for every 10% reduction in drag, range can be increased by 5%.
Tesla reported in a SAE article in 2013 that the drag coefficient improvement between the early concept and final Model S design was 0.08 using digital simulations. We estimate that this improvement helped to increase vehicle range by 50 miles.
Every detail matters when you're trying to achieve minimal drag, and by looking at some recent EV models we can see how carmakers are currently approaching the aerodynamic challenge.
There are certain features specific to EVs that can be used to reduce wind resistance. The flat vehicle underbody, for example, moves airflow quickly and smoothly to the rear. You don't often see sharp edges on the front of EVs – and that's certainly true for Faraday Future's FF91. Its smooth, rounded nose will help airflow move quickly to the underbody, where a lot of work would have been done to manage how that flow interacts with other parts of the car – namely the wheels.
The wheel arch and wheel areas typically account for a third of a vehicle's drag, so they're vitally important for aerodynamic efficiency. Faraday Future says that the FF91's Aerologic Wheels transform their shape kinetically, creating a more aerodynamic form at high speeds. You get much better performance if you can minimize the influence that the wheels have on the wake and help ease airflow to the rear of a car, and a closed-off wheel design can do this.
Aerodynamic efficiency can take many forms, and we don't necessarily agree with comments about the 'boxy' design of the Chrysler Portal concept having a negative effect on drag. With the appropriate time and tools for the job, you can aerodynamically optimize just about any shape. Besides, the Portal shares a lot of common attributes with the FF91 – a careful treatment of all edges and a very sleek surface, a fascia that doesn't have a large cooling opening, and a smooth, highly engineered wheel arch design.
When FCA engineer Ashley Edgar says that "smart is the new sexy", we get what she means in respect to the Portal. Look at the way the big windshield sweeps up to the top of the vehicle – that's sleek and aero-efficient. The unusual geometric design on the side of the car is bold, without necessarily causing aerodynamic problems – so long as you avoid a 'stair stepping' effect which creates obstacles for the airflow.
Cooling requirements are different for EVs, that's why you don't have predominant front grille openings on FF91 or the Portal. And that's certainly true of the VW I.D. Buzz which harks back to the classic Microbus from the 1950s and does away with the grille completely. This concept manages to be both retro and futuristic – and looks like it has been optimized for aero-efficiency. The surfaces appear to be beautifully sculpted and it has a very clean shape overall.
All of the models we've mentioned here, and EVs in general, have unifying aerodynamic aspects which contribute to minimizing wind resistance. If you work on these areas early enough in the design process you can find the trade-offs that enable the vehicle to perform better and increase range.
While these cars may have zero emissions, real-world performance still matters a great deal to EV drivers – and that extra 50 miles could make all the difference.