The Koenigsegg Regera is Koenigsegg's newest car, and is a hybrid. However, unlike other "hypercars," like the Holy Trinity, the Koenigsegg doesn't have a gearbox. I'm assuming that it uses some sum of motors to get the car moving off the line, and also uses a motor to "spin up" the engine, so it doesn't need a gearbox, but is this how it actually works? How can such a high performance car work without a gearbox? I feel like there's some torque converter in there somewhere...
Well, you have posted the link to the website, where they explain it, and also give this image:
There are three E-motors. Two on the axes, and one on the same shaft as the combustion motor (C-motor), which connects to the axes via a hydraulic coupling and a differential with a ratio of 2.73
Now, let's play with that numbers. The C-motor has its red line at 8250RPM, so it turns the axes at 8250RPM/2.73=3022RPM. The rear wheel dimensions are
345/30 R20 Y, which means they have a circumference of 2.17m. So, at max RPM, the car does 2.17m * 3022RPM = 6558m/min or 393km/h.
They don't state a top speed, but they write something like 20s from 0 to 400km/h. So it is feasible that the C-motor is connected to the axes via a 2.73 ratio differential.
However, the car would drive at 47km/h when the motor is at 1000RPM...
The solution is also written in the text of the website:
Koenigsegg has developed a clutch-slip mechanism that uses the hydraulic coupling to convert torque at medium/high speeds during fast acceleration. This allows the combustion engine to gain revs and power, thereby giving the sensation of a traditional downshift with the associated aural enjoyment, even without the traditional gearbox.
So, the answer to your original question is: They do have a torque converter like most other automatic cars, just a bit bigger / more sophisticated, so it can replace a gearbox.
(And I wonder why the put that third E-motor onto the shaft of the C-motor - a torque converter always steals some power, i.e. fuel/battery. But I guess that doesn't matter here, people are interested in peak performance, not efficiency / endurance)