The basics: In the LC 500h, its first application, the Multi Stage Hybrid System will consist of a 3.5-liter V6, a
hybrid transmission, and a lithium-ion battery pack. The hybrid transmission has an electric motor for motivation (and we're guessing a second for charging) and a four-speed automatic mounted to its rear, which either means inside or aft and in series. Why add ancient tech to a new hybrid system? Lexus says it preserves the connection between throttle input and engine speed that gets lost in a CVT. And while four seems like an insignificant sum in the face of nine- and 10-speed autos, remember that it is an infinite increase in gear count compared to CVT-packing hybrids.
But that doesn't make for the most exciting or familiar driving experience, as it affects both power delivery and the sound of the power being delivered. This is where the four-speed auto comes in. Based on the limited details Lexus has shared, our hunch is that the hybrid transmission will meld some form of the existing Lexus Hybrid Drive system with two more planetary gearsets, or the basic guts of a four-speed auto. This will provide the four fixed ratios and the feeling of actual shifting gears – because there will be actual gears shifting. (Students of history will recall that a
GM/Daimler/
BMW hybrid transmission joint venture produced a two-mode system that used two electric motors and a series of planetary gearsets providing four distinct gear ratios. Knowing Toyota, we're guessing this new hybrid system is simpler, more efficient, and in some way ingenious.)
That gear shiftiness means the engineers were able to add the first manual mode for a Lexus hybrid. It is imaginatively called M mode and should not be confused with the M button from a certain manufacturer with an M in the middle of its name that makes cars plastered with the letter everywhere possible.
