When the Koenigsegg Regera made its debut a little over two years ago, news that the hypercar would arrive without a transmission was a shock to many. No gears, no CVT, nothing. Thankfully, Jason Fenske of Engineering Explained is here to help us figure out how the Regera can move at all, let alone approach 250 mph, without a transmission.
So, with only one gear ratio at the vehicle’s disposal, Jason proves through the power of math that it is indeed possible to spin the wheels with what Koenigsegg calls “Direct Drive.”
A hydraulic coupling links the 5.0-liter V-8 engine to the 2.73:1 final drive, and once the Regera climbs above 30 mph, the system operates most efficiently. Until then, the electric drive system handles propulsion.
With this background knowledge in mind, Jason proves the point by working equations for wind and tire resistance using an arbitrary speed of a rather healthy 160 mph. The ultimate question is if the car can still break the tires free at that speed with appropriate torque, negating the need for gearing. By looking at the maximum amount of force the vehicle can apply and the weight distribution, the math provides the basis for the proof.
To be successful, the Regera needs 2,368 pounds of force to turn the tires at 160 mph, and at that point, there would be 601 pounds of aero and rolling resistance applied to the vehicle.
Long story short, because Jason is far more of an expert than us, he can say that the engine alone would not provide enough torque to do a burnout at 160 mph without a transmission.
Ah, but the Regera also features three electric motors. Those electric motors provide an additional 900 Nm (663.8 pound-feet) of torque. Adding that torque increases the torque curve and provides enough power to break loose the tires at 160 mph.
Not only does Jason lay out why the Regera forgoes a transmission, but he explains why the car would actually be worse off with the lower gearing that a transmission would provide. If the single-speed gear is capable of breaking the tires free with the vehicle’s torque at an incredible 160 mph, a more aggressive gear would offer zero benefit.
And this kind of technology isn’t just the stuff of supercars. The more pedestrian Honda Accord Hybrid also features similar engineering to directly power the wheels from the engine while recharging the battery.