using both motors for regen is definitely a good idea. I'm pretty sure the dual motor cars are doing that.
As for more regen power. It's certainly possible but it wouldn't get more energy back. The amount of kinetic energy is a given. Harder regen won't return more energy as there isn't more. If you have to use your friction brakes to slow down in a normal situation (not a red light or not someone cutting you off), you have been driving too fast or didn't keep enough distance. Harder regen isn't the solution to an aggressive drive style. It won't make it more efficient. Driving in a way that requires friction brakes in normal traffic is what makes your car inefficient.
One thing that is sometimes hard to understand is that the kinetic energy is not linear to the speed. Double the speed is not double the kinetic energy but four times! To double your speed you need four times the energy. When you regen you have four times the energy as compared to half the speed. If you regen at say 60 kW it would feel moderate at 70 mph, but it would feel much stronger at 35 mph and it would feel absolutely brutal at 20 mph. Not what you want. To avoid that Tesla reduces the regen power as you slow down. Drive 70, take you foot off. You will see the regen power gradually drop down as you slow down while it feels to you like it's the same deceleration.
As for more regen power. It's certainly possible but it wouldn't get more energy back. The amount of kinetic energy is a given. Harder regen won't return more energy as there isn't more. If you have to use your friction brakes to slow down in a normal situation (not a red light or not someone cutting you off), you have been driving too fast or didn't keep enough distance. Harder regen isn't the solution to an aggressive drive style. It won't make it more efficient. Driving in a way that requires friction brakes in normal traffic is what makes your car inefficient.
One thing that is sometimes hard to understand is that the kinetic energy is not linear to the speed. Double the speed is not double the kinetic energy but four times! To double your speed you need four times the energy. When you regen you have four times the energy as compared to half the speed. If you regen at say 60 kW it would feel moderate at 70 mph, but it would feel much stronger at 35 mph and it would feel absolutely brutal at 20 mph. Not what you want. To avoid that Tesla reduces the regen power as you slow down. Drive 70, take you foot off. You will see the regen power gradually drop down as you slow down while it feels to you like it's the same deceleration.