alt Hacker NewsOn a completely tangential note, has anyone ever tried a hybrid that was like a diesel-electric train? The engine just charges the battery. IIRC it can be much simpler, no need for gearing at all, the engine just runs at a constant speed and the battery handles delivering variable amounts of power.
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Rumor mill, but the Mazda RX9 may have their rotary engine powering the battery, which then delivers energy to the drivetrain.
"In that concept, the rotary engine functions as a generator to produce electricity for the battery and electric motor, rather than mechanically driving the wheels."
Excited to see if this becomes a reality
more: https://uscarcover.com/blog/2026-mazda-rx9-review-rotary-is-...
This was addressed explicitly in the video. It's far less efficient end-to-end, even though the gearing is theoretically simpler. Trains do it because diesel engines just can't produce the torque you need to move a train (at least, in the form factor of a locomotive), so they need to use electric motors.
one of the primary arguments of the video is that ecvt is a strictly superior solution. (and that diesel electric exists for massive torque conversion in trains, but loses efficiency)
The Chevrolet Volt and Honda’s recent hybrids work this way. They are mechanically even more simple than Toyota’s drivetrain.
The engine doesn’t run at a constant speed though, it responds to the amount of electrical power needed.
These are range extenders, and were used with the Fisker Karma, BMW i3 (as an option) and, most recently, the Mazda CX-30 with a Wankel engine.
The latter was sold in the UK/EU and was on the market for two years only.
Related: Honda's 2 Motor Hybrid System Explained. https://www.youtube.com/watch?v=-P_VChtMGK8
That is a series hybrid.
The Chevy Volt was one and the current Honda CRV is another. Both of them work mainly by the gas engine driving one of the electric motors as a generator while the other motor drives the vehicle. They have a simple eCVT transmission. However, both vehicles have a mode where they directly engage the engine to the transmission at highway speed cruising because that is more efficient.
Nissan has a series hybrid system that they have used in the Note that is only the series hybrid without the direct connect mode. That saves some money.
That's called a series hybrid: https://en.wikipedia.org/wiki/Hybrid_vehicle_drivetrain#Seri...
Ford is replacing their Lightning EV with an “EREV” gas generator.
RAM and Ford are about to launch range extended EV pickups with 609 miles of Range and 14,000lbs of towing
https://expeditionportal.com/the-extended-range-ev-influx-is...
Called a series hybrid, and it has been done. However gears are more efficient than a generator -> motor, and charging a battery adds even more losses. Thus if the engine is running anyway you are better off just mechanically connecting it to the wheels.
Trains don't do the above in large parts because the gears needed either wouldn't fit in the allowed space. (we may not be able to make them large enough either - that problem is solvable but may not be worth it)