Honda IMA is closer to a regular car's drivetrain, while the Toyota Hybrid Synergy Drive is closer to that of an electric car.

The Honda IMA takes a regular car's drivetrain and substitutes the transmission's flywheel with an electrical motor, which is connected to a battery pack and control electronics. The motor is only good for assisting the gasoline engine, not powerful enough to move the car on its own except under very rare circumstances (such as maintaining speed under 50kmph on a stretch of flat road). The moment you let your foot off the brake, the gasoline engine has to start running.

The rest of the Honda IMA drivetrain is the same as a regular car-- Engine crankshaft connected to either a multispeed geared transmission and torque converter (such as on the Accord Hybrid), a friction-belt-driven CVT transmission and torque converter (current Civic Hybrid), or a manual transmission with clutch (an option on the first-gen Insights).

The Toyota Hybrid Synergy Drive on the other hand does not have a conventional transmission like the Honda IMA. Instead, it uses a Power Split Device, which is a simple planetary gearset that combines the power from two electrical motor/generators (MG1 and MG2) and the gasoline engine. The entire PSD assembly is directly geared to the wheels, without a torque converter or clutch. This is similar to an electric car, which can have direct gearing to the wheels without a clutch or torque converter, because electrical motors can exert maximum torque at 0 RPM.

The Toyota Hybrid Synergy Drive, like an electric car, can move the car under electric power alone. How the Power Split Device transmission in the Hybrid Synergy Drive works: http://www.eahart.com/prius/psd

Personally, I like the Toyota system better. It's MUCH simpler than the Honda IMA system, with just 22 moving parts in the Prius PSD vs. about 100 in the Accord Hybrid's normal 5-speed automatic transmission gearbox and torque converter.

The PSD eliminates the need for multiple gear ratios (which means no gear-shifting wear-and-tear), does not have a hot-running torque converter (which means the tranny fluid lasts A LOT longer), and no clutch or CVT belts. That means the Toyota system has far fewer potential failure points and would be more durable.

P/S So a Prius will have less wear and tear issues. So to those who have always maintain that a prius is expensive to own because of battery failure, that's BULLSHIT!!! like someone who had mentioned above there are HELL lots of Prius running around the world that is easily more than 10 years of age. Like I have always said don't bash for the sake of bashing. If you wanna bash, please read or else you will be making a fool out of yourself.

This post has been edited by cody1508: Feb 21 2012, 05:10 PM

The PSD itself acts as a CVT.

This post has been edited by cody1508: Feb 21 2012, 04:59 PM

-Toyota announced today that the Prius C sold 1,201 units in just the first three days it was on sale, outsells monthly totals of Chevy Volt, Nissan Leaf in three days.

-If anything, those 1,201 sales are not as impressive as the C managed in Japan (where it is badged 'Aqua') – Toyota obtained 120,000 orders in the first five days it was on sale.

-Prius V sold about 8,400 units in the U.S. in the first ten weeks.

http://www.autoblog.com/2012/03/16/toyota-...lt-nissan-leaf/

This post has been edited by cody1508: Mar 17 2012, 03:47 AM