Feature: 2010 Honda Insight vs 2010 Toyota Prius

[Tideland Prius]

At this year’s edition of the North American International Auto Show in Detroit, it was just like old times, as two senior hybrid nameplates squared off from opposite sides of the room. In one corner, the 2010 Toyota Prius, the first mass-produced hybrid, was unveiled in its third generation. And in the other was the 2010 Honda Insight, a name used on the first hybrid to come to North American shores, and now revived on an all-new model.


Originally the only game in town, the Prius and Insight are no longer alone. Both companies make other hybrids, while General Motors, Ford, Nissan and Chrysler also have models on the market, and other companies have them on the way. The Prius still commands the lion’s share of the gasoline-electric market, to the point that it’s almost become a generic name for hybrids with many customers. Honda, meanwhile, has brought back the name of the cute-n-funky little two-seater that introduced us to the idea, in the hopes that buyers will reconnect with it. So how do the two measure up?


Full Article

[Rybold]

Interesting article. Somewhat limited, but still some good stuff.

Any predictions on whether you could fit a mountain bike in the back of the Insight?
"the Prius is the larger of the two: a 2700 mm (106.2 inches) wheelbase to the Insight’s 2550 mm (100.3 inches), and a body length of 4460 mm (175.5 inches), to the Insight’s 4376 mm (172.2 inches). The Insight is also smaller than the Honda Civic Hybrid"


"The Insight’s engine also includes a system called Variable Cylinder Management, or VCM, which stops firing on all four cylinders during deceleration to save fuel and decrease resistance to allow the motor/generator to more efficiently generate electricity and charge the battery."
-I understand how this saves fuel, but I don't understand how it would decrease resistance. Isn't it still engine braking? I'd think the only way to "decrease resistance" would be to disengage the engine from the transmission.

[Mike Dimmick]

Originally Posted by Rybold

"The Insight’s engine also includes a system called Variable Cylinder Management, or VCM, which stops firing on all four cylinders during deceleration to save fuel and decrease resistance to allow the motor/generator to more efficiently generate electricity and charge the battery."
-I understand how this saves fuel, but I don't understand how it would decrease resistance. Isn't it still engine braking? I'd think the only way to "decrease resistance" would be to disengage the engine from the transmission.

The current Civic Hybrid (and presumably the Insight) can leave the valves open through the engine cycle to reduce the pumping loss. It's still moving the piston, obviously, so moving air in and out through the intake and exhaust valves, but no compression occurs. I'm not sure how this is achieved, but my guess would be a special cam on the camshaft that can be selected.

It's not possible to disengage the engine from the transmission and get regeneration because the motor in Honda's IMA (Integrated Motor Assist, remember) simply takes the place of the flywheel in the engine. There still is a flywheel but it's much smaller.

The old Insight Central site is still up, and you can read about the IMA system here. The original Insight didn't have the ability to 'disable' cylinders that the HCH and new Insight have. The first generation HCH could disable up to three cylinders, the second generation extends this to all four.

[usbseawolf2000]

I thought VCM disables cylinders by closing the valves.

[richard schumacher]

Insight: no HSD. 'Nuff said.

[qbee42]

Originally Posted by usbseawolf2000

I thought VCM disables cylinders by closing the valves.

Yes. Opening the valves increases pumping loss, since air is moved through the cylinders. With closed valves you compress air, but the compressed air pushes back when it uncompresses. The net work is zero, other than frictional losses.

Tom

[SageBrush]

Cylinder deactivation – Displacement on demand – Variable engine displacement

It 'sounds' like a great idea; I still don't understand why fuel economy is not better than seen in practice. Some implementations of VCM alter the phase of half of the valves in order to recycle exhaust in the manifold -- rather like an Atkinson engine, if I understand correctly.

[MSantos]

Originally Posted by SageBrush

Cylinder deactivation – Displacement on demand – Variable engine displacement

It 'sounds' like a great idea; I still don't understand why fuel economy is not better than seen in practice.

Oh, but it can be at least some of us use it regularly. And the highway or (low speed steady state driving) at the hands of a good driver is where you see the highest gains.
This is precisely why the Civic Hybrid was selected for the Guinness world record across the US last November (68 MPG in winter like conditions with 3 people + gear on board).

Of course, the feature is there but rarely leveraged by the "just drive it" and heavy footed crowd. That is why the new Insight's instrumentation is taking it to the next level and prompting/enticing the driver to leverage these and several other features more consistently.

Cheers;

MSantos

[Rybold]

Thank you for the explanations about reducing engine braking. I think closing the valves would work. It would create an adiabatic system that would essentially do what qbee42 said. (I studied the Carnot Cycle (isotherms/adiabats) extensively back in college. It's been several years but I still remember how it works).

The mountain bike! What about the mountain bike???? Will it fit in the Insight?
(scroll up to see fancy picture)

[JSH]

Originally Posted by Rybold

The mountain bike! What about the mountain bike???? Will it fit in the Insight? (scroll up to see fancy picture)

My guess? Yes, with the seat and front wheel removed. That is how I put my bikes in the VW and Prius. You won't know for sure until the Insight shows up in dealerships. The limiting factor will be the height of the hatch opening.

Here is a picture of the Insight and some bikers: