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Right, and the difference in efficiency between 3rd gear and 4th gear was about 2%. You lose that much by introducing the best gear reduction "transmission" like the Borg Warner unit used in the Aptera. And Tesla used a "proper" transmission, and they discarded it after having similar problems. The torque of an electric motor is much harder to deal with than an ICE. There is an order of magnitude of difference in the quickness of the increase in torque, and this is very hard on the gears.
Back on topic: it is the buffering function of the battery that gives a series hybrid all of it's major advantages. So, I don't think it should be eliminated.
1) You can plug in and charge the battery which is the most efficient way to get electricity in the car. An electric motor is the most efficient way to power a car, so this makes sense.
2) When the battery is nearing depletion, the ICE can be started to spin the generator. This is best done at a fixed RPM, so the engine can be run at it's peak efficiency. The valvetrain and intake and exhaust can all be optimized for this RPM; with no need for variable valves. (Although on one recent genset, they designed it without a throttle and used the valves to control the RPM, I think?) It might be possible to eliminate the throttle altogether?
3) The ICE needs to only meet (or slightly exceed) the average load, and not the peak load. So the displacement of the ICE is minimized, and then along with that, the cooling system can be minimized (which pays dividends in lowering the aerodynamic drag), and the fuel tank and exhaust systems are smaller and lighter weight. The ICE will warm up more quickly.
4) Since the genset can charge the battery more quickly than it gets depleted, the ICE only has to run periodically. This obviously save a lot of fuel, too. The cooling system can have an active louver to closed when the ICE is not running, or during warm up to get to optimum temperature as quickly as possible.
So, having a battery pack of a certain size depending on the efficiency of the car makes a very big difference.
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