Do Hybrids Really Make Sense?

[jamesqf]

Originally Posted by MetroMPG

If the question you're getting to is: Can you build a small, light, aerodynamic, LRR vehicle with smart ICE management which outperforms the fuel economy of today's mass-market hybrids?

The answer is obviously YES.

But then you can take that small, light, aerodynamic, LRR vehicle, add a hybrid system to it, and get even better mpg.

So bottom line: have we decided whether the Earth is flat or not?

[NeilBlanchard]

The most important factor to vehicle efficiency is the efficiency of the drivetrain.

Since electric motors are ~3X more efficient that ICE's, any drive train that can leverage the electric portion of it's drivetrain enough, will end up being more efficient overall. Another way that hybrids improve is to use the electric motor to allow the ICE to run in a more efficient way, and to work around the weaker aspects of the ICE; one of which is idling and having high enough torque to accelerate the car in the most demanding situations.

[redpoint5]

Originally Posted by EVmetro

It still takes a certain amount of energy to drive a car of a certain weight and cd, and I don't fully understand how the Atkinson engine coupled to an electric motor benefits this.

It may be helpful to read about BSFC and pumping losses. You are correct that it takes a specific amount of energy to go a specific speed, but different speeds and loads on an engine greatly affect how efficiently it is producing that energy. An gasoline engine can be 5x more efficient when accelerating compared to cruising at a steady 40 mph. That's because large throttle openings minimize pumping losses and larger quantities of fuel maximize thermodynamic efficiency. It's not efficient for all cylinders of an engine to work against a vacuum while producing 20% of their designed power.

Whenever an engine is putting around, barely producing it's peak potential, it's operating in a very inefficient way. It can be more efficient to generate a little extra electricity when the engine is operating at peak efficiency, and later use that electricity to move the car when it would otherwise be using the engine in a very inefficient way (parking lots, low speeds, etc).

Originally Posted by vibrating_cake

No, the ICE in a Hybrid is no more or no less efficient than the ICE in a non-hybrid.

This statement is only true sometimes. Sure, some vehicles have the identical ICE in both their hybrid and non-hybrid models, and the electric system exists mostly just to boost acceleration performance. However, some cars, such as the Prius, specifically engineer the engine for efficiency. The Prius engine is 1.8L and produces only 98 HP compared to a VW 1.8L engine that is designed to produce 170 HP. Which engine do you think is more efficient for maintaining a steady 55 mph cruising speed where only 15 HP is needed?

[Hersbird]

I don't think there would be an argument with 2 equally capable cars, one a hybrid and one a ICE only the hybrid will get better economy. Now say you take a Prius keep the same motor, remove all the electric parts, add a manual transmission you might end up better highway economy and less city but it will be a bit of a dog. Probably acceptable to most here wanting economy over power but not as snappy as a normal Prius. Now what if Toyota built that car from the factory and the cost was reduced $1000's of dollars. The extra money spent on the hybrid part may not deliver enough extra economy to justify the price. The environmental impact of the car without extra batteries would be better as well. Alas Toyota won't do that, and many Prius owners have proven they want a car that is instantly recognizable as a hybrid. Not having to look for a badge or even a giant decal on the side.
I haven't seen it mentioned but what about turbo diesel? Don't most turbo diesel's thermal efficiency surpass even the Atkins diet motors? Added cost on a TDI is similar to added cost of a hybrid system.

[Fat Charlie]

They seem to have mated diesels and electrics pretty effectively on trains.

[3-Wheeler]

Originally Posted by RedDevil

....The Fit Hybrid is heavier, yet much more economical than the comparable CVT trannied Fit. It is also faster.

My dad bought it because it is more pleasant to drive.
Small cars with auto trannies usually have a horrendous latency when you accelerate. CVT drums take ages to spin up. Conventional trannies need a second or more to shift down, then think again and shift again.
Not the Fit Hybrid.....

Bingo!!

When I drive my wife's Honda Fit, I get into a subtle struggle with the automatic transmission. It always shifts at a time when I do not want it to.

The engine has enough low-end torque to make it up a slight hill in the current gear, but ....no...., the automatic insists on shifting to a lower gear and over revving the engine across the entire hill. ....ARG.... Does the same thing is Sport Mode.

That situation would be a moot point with a Prius or Volt.

Jim.

[3-Wheeler]

Originally Posted by Xist

......That same page says that people almost never need to replace hybrid batteries, but I see Prii with worn-out batteries on Craigslist all of the time......

I have a Gen1, year 2000 Insight with an original battery. Capacity is about half, but then again, I do "normal" Insight related battery maintenance to keep it healthy too. Not sure if the same thing applies to a Prius, but would not be surprised if it did.

In that regard, a Prius might be more of a "techy" car similar to the Insight.

Jim.

[EVmetro]

Originally Posted by vibrating_cake

is this thread not about hybrids making sense, and actually making a difference via their identicle other? i.e. the earlier Jazz/Fit comment, all being equal, would the hybrid be better/make sense?

The confusion is my fault. That thread title suggests the spirit of a troll (and I often am), but I do not actually know the answer either. I am in fact interested in finding the answer, so I probably should have titled the thread a little better. I suppose that a debating format can be very educational as well though... Lots of great info flowing here, thanks to all!

[MetroMPG]

But then you can take that small, light, aerodynamic, LRR vehicle, add a hybrid system to it, and get even better mpg.

Comment of the Day nominee!

[RedDevil]

Originally Posted by 3-Wheeler

Bingo!!

When I drive my wife's Honda Fit, I get into a subtle struggle with the automatic transmission. It always shifts at a time when I do not want it to.

The engine has enough low-end torque to make it up a slight hill in the current gear, but ....no...., the automatic insists on shifting to a lower gear and over revving the engine across the entire hill. ....ARG.... Does the same thing is Sport Mode.

That situation would be a moot point with a Prius or Volt.

Jim.

And the Fit Hybrid of course.

I've driven some CVT trannied cars and could not believe I'd like the Honda hybrids, as they too have a CVT.
But the hybrid system does away with the lag.
It is more economical, but who cares? We maybe, but not my dad.
It is a better car, that made him buy it.

Even so, the EV and plugin hybrids do have an edge.
It is nice to regenerate power on braking, but it is even nicer to have a constant supply trickle in.
There will always be more opportunities to use electric power (to boost economy) than to regenerate it.
Do I want a plugin booster pack for my hybrid, would that help?
Sure, a lot.

And there is another advantage of a hybrid; it makes a (semi) EV conversion a lot easier.
The engine is there. The electronics are there, by and large.
I feel the itch