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Once upon a time there were cars with a "normal" 4 speed (+reverse) gearbox and an added "overdrive" box (that if I recall correctly could only be used in 3rd a

• kwhitefoot 7y ago
  Loads of cars had an overdrive and it made a significant difference to fuel economy at high speed. I think the difference here is that the Taycan has a kind of automatic gearbox that can operate while under hard acceleration whereas, as far as I remember, you only pushed the overdrive button when you had reached cruising speed.
  • jaclaz 7y ago
    Yes, that is part of the evolutions I mentioned, what I meant essentially was saying that a two speed gearbox (electrically/hydraulically operated) reminds me more an overdrive box (which is actually a two speed gearbox electrically/hydraulically operated) than an actual 4/5/6 speed manual or automatic gearbox. The actual use of the old overdrive was to lower revs of the engine (please read as save fuel) at a given speed, or (I know, not the actual intended use) to increase top speed, which is exactly what the new Taycan gearbox seemingly is used for (automatically, not manually, of course). I remember a diesel Volvo station wagon (must have been a volvo 240 or 244) where in order to overtake someone at 120-130 kmh, the procedure was: 1) turn A/C off 2) accelerate as much as possible in 4th gear 3) push the override button that gave just a little more speed.