Do Hybrids Really Make Sense?

[serialk11r]

Originally Posted by Hersbird

Modern direct injection can eliminate the throttle then add cylinder deactivation and variable cam profiles to that. A non-hybrid can also be optimized to have just enough power for cruising speed and the ability to add more power when needed.

I don't think you understand what direct injection does. It does not eliminate the throttle.

The most sophisticated variable cam profile systems allow throttle plate elimination at the cost of greater valvetrain power consumption. Honda's R18 and 3-stage VTEC motors allow a rough approximation of this capability, allowing a greater proportion of high throttle position operation.

Even without the throttle restriction, thermal efficiency is still horrible at low load because the combustion temperature and pressures are so low and mechanical efficiency is also low. There is no getting around a combination of downsizing + power adders, shutting the engine off, and using longer gearing.

[user removed]

Originally Posted by Gasoline Fumes

I think a hybrid makes a lot of sense for regular drivers, especially in city driving. My parents are looking for a newer car, and I'm convinced the 2nd gen ('04-'09) Prius is the best option. They do a lot of city driving and don't hypermile. No non-hybrid will get even close to the Prius city MPG. Especially with an automatic. And at least around here, a used Prius doesn't seem more expensive than a similar-sized non-hybrid.

For hypermilers, I think most of the hybrid advantage doesn't apply. I averaged over 70 MPG last Summer in a '91 Civic Wagon. I don't think a Prius could do much better. But I'll try to prove myself wrong every chance I get!

"At least around here a used Prius doesn't seem more expensive than a similar sized hybrid"

If so then the additional cost of the hybrid components could offset the additional fuel cost of the nonhybrid option.

Once the hybrid battery warranties have expired right at the ten year mark, which happens to be the average age of vehicles on the road in the US today then the value of the hybrid plummets. Which would you rather have, a 2003 Prius or a 2003 Echo? Remember the new price difference was almost double the original price for the Echo, at least. Now how about the Echo and a 5000 GALLON gas card.

The highest Echo mpg in the garage here is high 60s or over 300k miles on that 5k gas card (price difference).

The Prius is not driveable with a bad hybrid battery and few (very few) hybrids beat that Echo's mileage. In my manual Echo 45-47was fairly easy without driving slower than most traffic.

regards
mech

[oldtamiyaphile]

Originally Posted by jamesqf

Again, just not true. Providing, of course, that the hybrid vehicle is properly designed and sized, rather than just being tacked on as an afterthought. It's all down to right-sizing the engine to be efficient at cruise, while using the electric motor for acceleration.

I think there might be some skewed perspective on here from US dwellers. I can buy a turbo diesel van that will match a Prius on the highway. It's only in the city that a Prius does better (no stop start or if would be pretty close). Considering the Prius' much better CD, I can only assume that the Prius hybrid system is a tacked on afterthought then?

[oldtamiyaphile]

Originally Posted by Old Mechanic

Once the hybrid battery warranties have expired right at the ten year mark, which happens to be the average age of vehicles on the road in the US today then the value of the hybrid plummets.

The cost of ownership (from new) I've done for both EV and Hybrids, the break even point is right about the time the battery is likely to need replacing, and the car's value drops to scrap. It really comes down to taking a gamble.

In Europe EV's at five years old are only worth scrap value as people won't buy them in case it needs a new battery.

[Gasoline Fumes]

Originally Posted by Old Mechanic

"At least around here a used Prius doesn't seem more expensive than a similar sized hybrid"

If so then the additional cost of the hybrid components could offset the additional fuel cost of the nonhybrid option.

Once the hybrid battery warranties have expired right at the ten year mark, which happens to be the average age of vehicles on the road in the US today then the value of the hybrid plummets. Which would you rather have, a 2003 Prius or a 2003 Echo? Remember the new price difference was almost double the original price for the Echo, at least. Now how about the Echo and a 5000 GALLON gas card.

The highest Echo mpg in the garage here is high 60s or over 300k miles on that 5k gas card (price difference).

The Prius is not driveable with a bad hybrid battery and few (very few) hybrids beat that Echo's mileage. In my manual Echo 45-47was fairly easy without driving slower than most traffic.

regards
mech

I was thinking about something a little newer. A 2007 Yaris with an auto (preferred, but not required) is rated at 29 MPG city. The same year Prius is rated at 48 city. The battery packs can be rebuilt. Or purchased rebuilt for $1000 with exchange. Another plus of the Prius is the versatility of a 5-door hatchback. Coming from a minivan, a small sedan is going to be disappointing. Next size up is a 2007 Toyota Matrix, but that gets only 25 MPG city. Even my neighbor's 2007 Honda Fit (5-speed manual) only gets 28 MPG city. If it was for me, I'd go with the Fit (for sale soon) and hypermile the wheels off it. But I think a Prius makes the most sense for my parents in a hilly city.

[Xist]

Originally Posted by oldtamiyaphile

the break even point is right about the time the battery is likely to need replacing

That is what I have calculated, but there are far more factors than I know how to take into account.

I have mentioned the woman that said a Prius cost the same as any other car.

Then why was she not driving a Tesla. Then she clarified that it cost the same as a Civic or Corolla.

How did she figure?

So, hypermiling a Prius versus an Echo?

Driving a Prius like a maniac compared to an Echo?

[Hersbird]

Originally Posted by serialk11r

I don't think you understand what direct injection does. It does not eliminate the throttle.

The most sophisticated variable cam profile systems allow throttle plate elimination at the cost of greater valvetrain power consumption. Honda's R18 and 3-stage VTEC motors allow a rough approximation of this capability, allowing a greater proportion of high throttle position operation.

Even without the throttle restriction, thermal efficiency is still horrible at low load because the combustion temperature and pressures are so low and mechanical efficiency is also low. There is no getting around a combination of downsizing + power adders, shutting the engine off, and using longer gearing.

Some do it with the valve timing and some just can do it with the direct injection.

From this article, "Some engines with direct gasoline injection do not have a conventional throttle because the throttle is not used to control engine speed and power. The engine computer does that by varying the time and amount of fuel that is injected into each cylinder. Eliminating the throttle means there is no restriction to incoming air and little or no vacuum in the intake manifold. This reduces the normal pumping loses caused by the throttle plates and intake vacuum for improved engine efficiency."
Gasoline Direct Injection

From wiki, " In addition some engines operate on full air intake. That is, there is no air throttle plate eliminating air throttling losses in some GDI engines, when compared to a conventional fuel-injected or carbureted engine, which greatly improves efficiency, and reduces piston 'pumping losses'. Engine speed is controlled by the engine control unit/engine management system (EMS), which regulates fuel injection function and ignition timing, instead of having a throttle plate that restricts the incoming air supply. Adding this function to the EMS requires considerable enhancement of its processing and memory, as direct injection plus the engine speed management must have very precise algorithms for good performance and drivability."
Gasoline direct injection - Wikipedia, the free encyclopedia

These motors I think always still have a throttle body but it's for startup and if something goes wrong with the system.

Diesels have been using direction injection without throttle for a long time with no fancy valve systems. It's their direction injection that made that possible

[mikeyjd]

Originally Posted by Hersbird

Modern direct injection can eliminate the throttle then add cylinder deactivation and variable cam profiles to that. A non-hybrid can also be optimized to have just enough power for cruising speed and the ability to add more power when needed.
What is missing on current cars with cylinder deactivation is the ability to lock it in and then add more throttle to put the motor in a more efficient throttle/rpm as soon as you add just a little throttle the computer kicks you out of cylinder deactivation.
The 2015 Chevy trucks now have direct injection and cylinder deactivation. I am interested in how well they might do in real world but would also like to see new engines built from the ground up with this in mind rather then add-ons to old motors which is what Chevy has done.

My friend Kyle has the 2015 Silverado with cyclinder deactivation. He says that he consistently gets 28mpg highway when he's trying to stay in cyclinder deactivation mode.

[jamesqf]

Originally Posted by oldtamiyaphile

I think there might be some skewed perspective on here from US dwellers. I can buy a turbo diesel van that will match a Prius on the highway. It's only in the city that a Prius does better (no stop start or if would be pretty close).

Maybe so, but that's the Prius, which is not really optimized for highway cruising. I doubt your diesel will match an Insight's highway mpg.

[redpoint5]

I just ran the numbers on a new base model Ford Fusion vs the base model Ford Fusion hybrid and found the break even point is around 11 years of ownership at current fuel prices. I also ran the numbers on a base model Honda Accord w/CVT vs a base Honda Accord Hybrid and found the break even point is 12 years. This assumes 12,000 miles per year.

However, on used cars the break even point is much shorter. Buy a 2010 Camry hybrid, and the price premium you pay over the base car will be made up in 6 years. Every year thereafter is profit.

I don't think hybrids make financial sense when buying a new car, but then buying any new car doesn't make financial sense. Used however is a different story. A used hybrid can make a lot of sense, especially given the fear people express here regarding battery replacement. Those very fears drive down the value of used hybrids, and that benefits the buyer.

In the end you have to buy the right tool for the job. If a person lives in an urban environment, owning any vehicle might not make financial sense. Many people in Portland forgo the high cost of owning a vehicle and just bike or MAX everywhere.

If low cost of ownership is among the most important criteria to you, then a pure EV makes all kinds of sense, especially if your family has 2+ cars.

I'm waiting for the Tesla Model S to depreciate to the $20k price point, but maybe by then other EVs will be more attractive. I'd like to give up my TSX for an EV, but dang if it wasn't so much fun to drive!