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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...

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Well, you have posted the link to the website, where they explain it, and also give this image:

enter image description here

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)

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    I agree with most of what you've said here. The third "E-Machine" on the front of the ICE provides a generator source for the batteries, provides extra torque for the ICE when needed, plus is probably used as a starter for the ICE. All three "E-Machines" can be used for regenerative braking. I'm wondering about the "clutch-slip mechanism" and whether it's actually a torque converter ... but it may just be mumbo-jumbo talk for sales purposes. If it is a TC, it can use a lock-up just like any other TC to stave off power losses at speed. – Pᴀᴜʟsᴛᴇʀ2 Aug 12 '16 at 11:29
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    @Pᴀᴜʟsᴛᴇʀ2: D'oh, you're so right about the 3rd E-motor! About that clutch-slip mechanism: It seems it works as torque converter at low speed, can lock-up at higher speed, but can also be switched back to "TC-mode" at higher speed for more torque and that "kick-down feeling". – sweber Aug 12 '16 at 12:01
  • Are there any other cars that use hybrid technology in this fashion (using a motor on the engine output shaft), or is Koenigsegg the first one? – wcarhart Aug 12 '16 at 18:12
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    @ThePickleTickler the Honda CR-Z is a manual transmission hybrid which does exactly that. Apparently Honda has been making hybrids with the motor coupled to the engine output shaft since 1999 in one flavor or another. – Lathejockey81 Aug 13 '16 at 15:52

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