Publice, though your idea has merit, there are some concerns that I want to inform you about.

First, 'breaking' the driveshaft to install a motor will not give you much room or much structure to transmit the horsepower. A reasonable system will probably not fit in the driveshaft tunnel. And do you mean to run the motor and engine together? With the motor spinning in the driveshaft? You'll pass 600 amps through slip-rings?

Torque will be a problem--most electric conversions use and NEED the transmission, because the motors are typically under 50 (or even under 20) horsepower. They don't have enough torque to start the car, even though a 4.11 rear axle. The gears increase that torque.

Next, keeping the entire gas-engine in place, though easy, leaves you with so much extra weight. Your additional electric motor and batteries will add 500-1000 pounds to the system--you really want to lose some of that extra.

Also, a modern car with say a 150-amp alternator can generate 1800 watts of electricity. At 746w/horsepower, you can only harness about 2.4 hp from that original engine with the alternator at full-load. And we already said we had a 20-50 hp electric motor, so it won't keep up. Need a bigger alternator. or eight.

Current hybrids (Prius) benefit from the fact that the 28hp electric can team with the 70 hp gas engine to provide reasonable (not fast) acceleration. I don't really understand if you intend to 'team' these as a combined hybrid or just 'cut' the driveshaft and power with electric only, but they both need to work through the gearbox.

But lastly, control will be the biggest problem I see. Will you put the gas engine under computer control to allow it to throttle appropriately to charge, or will you use a manual control? Will your accelerator pedal only operate the voltage to the drive motor? If you intend to operate as a combined hybrid, you'll need a computer to decide which motor is providing the power. Otherwise it'll be like running the engine with the starter engaged.

The inverter to control the electric runs $1000. The motor is expensive. The batteries are expensive. I don't know where you got your $1000 estimate. And all the added weight (and none deleted)I'm dubious if the fuel consumption would decrease.

HI HRENCH--THERE MAY BE PROBLEMS OF COURSE BUT THE ELECTRIC MOTOR WOULDNT WEIGH ANYWHERE NEAR 1000 POUNDS.REAR HUB MOTORS NOW AVAILABLE WEIGH AROUND 100 POUNDS EACH--12 LEAD ACID BATTERIES OR THEIR EQUIVELENT MAY BRING THE EXTRA WEIGHT UP TO 500 POUNDS.THE SYSTEM IS ONLY A BOOST SYSTEM NOT A MAIN DRIVE SYSTEM .THERE ARE CAR MANUFACTURERS IN EUROPE(http://www.just-auto.com/article.aspx?ID=89333) WHO ARE NOW PUTTING THE ALTERNATOR/STARTER MOTOR ON THE CRANKSHAFT FOR ENGINE BOOST PURELY OFF THE 12 VOLT MAIN BATTERY,WITH 12 TIMES THE BATTERY POWER(FOR EXAMPLE) THE BOOST WOULD BE EVEN MORE FUEL EFFICIENT.ELECTRIC VEHICLES BEING MADE LOCALLY WHERE I LIVE DONT HAVE A GEAR BOX AT ALL.

EXAMPLE OF CHEAP HIGH TORQUE ELECTRIC MOTORS AVAILABLE NOW- http://www.alibaba.com/countrysearch/CN-suppliers/Brushless_Hub_Motor.html

Maybe you should bolt your electric motor/alternator to the crankshaft pulley then and toss away the alternator and starter motor.This would eliminate some of the probs raised by Hrench.Might cost more than $1000 but I have seen full conversions costing up to $30 000.

sorry folks--just found it was in a honda production car-attached to the crankshaft-honda insight.$50 000. they reckon it was $30 000 overpriced.simple idea ridiculous price.insight held record for most mpgs of a production car.that new volkwagen will beat that record.250 mpg.a manufacturer of conversion kits would make a killing

Pub, I value your idea, but I think you still don't have the execution of it right. Those hub-motors you've directed us to are topping out at about 2000 watts. That's less than three horsepower. Even with four, you'll have a slow 'car.'--they look to be designed for carts or bicycles. You need 21,000 watts to equal a Prius.

And yes, three horsepower will move a car through a big-enough gear-train, but you're still adverse to running the motor through the geartrain. I can't understand why.

As for a 'boost' power, again, three hp isn't much.

As for installing motor as a starter/generator on the crank, yes, it's a fine idea--that article you reference talks about shutting the engine down at stoplights, yes, this seem reasonable. A combined generator/starter was done in the 1930's, called a 'starterator', but again, it doesn't engage the drivetrain to boost power--you'll need computer control for boost to allow the car to decide what power comes from the motor vs. the engine.

I think the reason the current group of hybrids all function as combined hybrids is because the other options don't work as well.