Am I correct in that the only Toyota hybrid that uses the synergy drive is the Prius? If true (or approximately true), why?
Once they put a boost circuit in the inverter to increase voltage to the electric motors over battery voltage they called it Synergy Drive. It's the same system in Highlander or a Camry or any Toyota hybrid newer than a generation 1 Prius
It's just marketing spin, all Toyota and Lexus hybrids are "series-parallel" or "power-split" hybrids with some variations. The 3rd gen Prius, Auris Hybrid (hatchback variant of the Corolla sold in some markets) and the Lexus CT200h all use the exact same powertrain, for example. Hybrid vehicle drivetrain - Wikipedia
i guess toyota would determine the technical name. not sure what terminology they use. it is their second plug in, with mostly gen 4 tech.
They only licensed some of the technology IIRC. I believe they licensed Gen 3 I do not know if they licensed any Gen 4 technology. I believe Ford uses a different transmission design than Toyota.
The first generation Ford Fusion Hybrid (and a few other Fords, also the Chrysler Pacifica Hybrid) uses power-split transmissions produced by Aisin Seiki - who also make the hybrid transmissions for Toyota. Toyota own 30% of Aisin Seiki, but I doubt Ford actually dealt with Toyota as it's Aisin's technology. Ford supplied the ICE, batteries and everything else outside the transmission. More recent Ford hybrids use a transmission designed and built in-house - but a very similar setup with planetary gearset, two motor generators, etc. EDIT: It looks like Toyota held some of the patents, so they did apparently do some patent exchange deal when developing the Escape Hybrid.
