Almost always running hybrid idea.
 

Since engines are not efficient when they are cold it makes sense that the longer they run in between startups the less fuel is wasted. Also a lighter car wastes less energy accelerating and braking. So why not make a hybrid car that is primarily an electric car with a small light engine that runs continuously at its peak efficiency rpm until the batteries are charged (even when parked)? The idea is that the engine is so small that it only has enough power to supply 80% of the electricity needed while driving and only does charging when the vehicle is stopped or when the trip is over. This smaller engine will save weight and dedicating all its output to moving the car when driving reduce lost energy due to the inefficiency of charging the batteries.

The only problem I could see is parking this car in a garage or other confined space.

Thoughts?

Sounds like a Volt. I agree though, its a great idea.

Alternator + Weedwacker motor... would run forever on a tank of gas

Except that 2-cycles aren't cleared for road use anymore :P

Moped motor :P

Hi,

This is called a serial hybrid: the Volt, the Aptera 2h, the Capstone S-Max, the older Mini hybrid, and others -- including diesel/electric train locomotives -- all use this set up.

Yes, the engine is run at it's peak efficiency, and so it can be much smaller than if the ICE was pushing the vehicle. There is no transmission or clutch; it is mechanically very simple.

They make 4-stroke weed wacker engines now.

Correction, diesel/electric trains are not hybrids. They do not store electricity, and use the setup because there were no good mechanical options at that scale.

2. the drivetrain losses from ICE to wheels are much more significant in series than in direct drive mode when you choose your engine and speed/gearing correctly.

3. BSFC generally improves (diminishingly) with larger engines. Volume vs surface area thing. The COX sized engine that runs all day is not as efficient at making power as a 200cc engine that can keep your car at 55mph for a long trip.