Some topics recently have talked about how EVs can disable regen sometimes (such as when the pack is too full, or too cold), and how it is disappointing to compare the way the car drives without the regen. There has also been talk of keeping regen active, but "shunting" the power created if the pack isn't ready to accept it. It got me pondering some things. Some diesel-electric hybrid trains have a form of regen where they power cooling fans when slowing down. They don't have any storage batteries. They accelerate by diesel engines running generators directly powering electric motors. When they slow down the motors go into regen mode and take the power to run fans that cool the diesel engines. That also got me thinking about how jets "reverse the thrusters" after landing to slow down quickly without overheating the brakes. On many jets, a metal flap extends to redirect the jet gasses backwards so that the jet engines are effectively running in reverse to slow the plane down. I was watching a show on salt flat cars and noticed they all used parachutes to slow down. An owner said they tried to use friction brakes but they just kept overheating and breaking. So, couldn't we apply some of these ideas to cars? For instance, lets say you are going fast and pressed the brake pedal... perhaps the car should extend some flaps to make the aerodynamics "dirty" to help slow the car without using the friction brakes? Some cars (like high end Porsches) have wings that extend at high speeds for more downforce, so the idea of some mechanical wing/flap/fin doesn't seem out of the realm of practical technical possibility. I suppose the car could intelligently blend aero braking with motor regen depending on speed, battery state, etc. Another idea would be to use excess regen to run fans in reverse. For instance, many cars have radiators fans that suck air through the radiators to cool the engine/motor/battery/etc. Perhaps as part of regen some (or all when needed) of the regen power could be used to run the radiator fans in reverse to help slow the car? Just some ideas I am throwing out there.