Consumer Reports tested the Prius at 55MPG highway. Considering a all-gas auto that gets 40MPG highway, that's a 37.5% better rating for the Prius. I know of no other technology that can improve fuel efficiency that much.

My brother in law has been driving a Prius since it first came out (on his third one) and he says his mileage is about 44. maybe the new ones are better (?) but the older ones did not get 55 mpg on the highway even at steady 65 mph (see attached).

 

Well, remember that hybrid technology is new, and improving. If you look at real MPG numbers for hybrids, they've gotten better over the years.

All I know is what I read: look up the issue of Motor Trend where they tested that new Ford hybrid rated at 47 mpg. They got 31 mpg on a combined test loop. That is horrible. And it's the same test they use for them all. The all gas Honda Civic got 35 mpg.

 

My brother in law has been driving a Prius since it first came out (on his third one) and he says his mileage is about 44. maybe the new ones are better (?) but the older ones did not get 55 mpg on the highway even at steady 65 mph (see attached).

Your chart shows 52.2mpg, which is only 5% off the claimed 55mpg. I would not be at all surprised to see that much variation between nominally identical cars or even with the same car under different conditions. Temperature, humidity, density altitude, fuel blend. Heck, the type and tread of the tire and also its state of inflation can have that much impact.

 

All I know is what I read: look up the issue of Motor Trend where they tested that new Ford hybrid rated at 47 mpg. They got 31 mpg on a combined test loop. That is horrible. And it's the same test they use for them all. The all gas Honda Civic got 35 mpg.

I did read that article. As I recall, the Prius was tested at over 50 MPG on the highway (52-53 as I remember). And CR tested their Prius at 55MPG, as already stated. You can look up the CR numbers online. Strantor's 59MPG while averaging 65MPH makes these numbers look realistic.

 

I recently took a trip in the prius from Houston to Hattiesburg MS, 460 mi. On the way there I drove conservatively, avg speed 65 mph, drafting trucks when convenient, and I got 59 mpg. On the way back I was in a rush, avg speed 85 mph, and I got 41 mpg. This is far better than you could get from a comparable sized all-gas car, but I think it could be better yet. I think that getting the engine involved in traction is a mistake.

With a parallel hybrid like the Prius once it is at a constant speed on the freeway the hybrid electrics are in a steady state (not charging or discharging) and do not increase the fuel efficiency! In a steady state of speed along a flat freeway all the motive power comes entirely from the gas engine, so it's just a gas powered car like any other.

So that same freeway fuel efficiency can be achieved identically from a non-hybrid vehicle, provided it has the same engine, air drag, weight, rolling drag etc. (Actually the non-hybrid would have an advantage that it is not carrying the weight of electric motor and batteries.)

It's a bit silly quantifying the hybrid's performance based on freeway travel. The weight of all that hybrid gadgetry pays back in city driving where the battery can assist in constant repeated acceleration, and in regeneratve braking. Ie; in slow start-stop city traffic.

 

It's not silly at all to quantify the hybrid's performance based on freeway driving. Toyota has several gas only cars with the same engine, air drag, rolling drag, weight (minus the hybrid stuff) etc which cannot come close to the hybrid's numbers on the highway.

 

Your chart shows 52.2mpg, which is only 5% off the claimed 55mpg. I would not be at all surprised to see that much variation between nominally identical cars or even with the same car under different conditions. Temperature, humidity, density altitude, fuel blend. Heck, the type and tread of the tire and also its state of inflation can have that much impact.

My point all along for hybrids and all vehicles is they NEVER return EPA figures in real world driving. The truth is that the average speed on a freeway with open flow is never 65, it's 70 or more where the gas mileage is really nosediving.

My main complaint is that the actual mileage people get in the real world is typically 20 - 40% lower than EPA numbers CONSISTENTLY which means it is not the driver problem, it's a non representative test.

As I said, my brother in law has been driving a Prius since they came out and he says his gets about 44 average. That's very good but nowhere near the ratings. He doesn't leadfoot and drives pretty normally. BTW: the median value on the graph below is about 47 mpg for 2278 cars reported. That's very good, but it's not 55.


FOR EXAMPLE:

I drive my 2012 Prius 3 127 miles a day back and forth to work on mostly HWY. I use cruise control and never take it out of ECO mode. I only average 45-47mpg according to computer . I have never gotten more than 430 miles to a tank. Can anyone tell me why the car isnt getting advertised MPG? I now have 16000 miles on the car.

http://priuschat.com/threads/prius-actual-gas-mileage-vs-advertised.123996/

i drive a 2007 Prius touring model and have been keeping detailed accurate records from time i bought the car new. i have both MPG per the car display as well as MPG gas Pump average. I live in Seattle WA, drive on some hills, do mostly in-city short trip driving and some occasional highway driving. My average gas milage per the gas pump calculation for the over 6 years I have been driving the car is 40.8 MPG, and for the car's display average calculation, it is 39.96.

http://townhall-talk.edmunds.com/direct/view/.ef7c05b

 

It's not silly at all to quantify the hybrid's performance based on freeway driving. Toyota has several gas only cars with the same engine, air drag, rolling drag, weight (minus the hybrid stuff) etc which cannot come close to the hybrid's numbers on the highway.

It's rather interesting that the freeway driving gas mileage of a hybrid can be significantly higher than that of a similar non-hybrid since all the energy is being provided by the gas engine under those conditions in either case. The difference must be a more efficient gas engine in the hybrid (which is often an Atkinson cycle type) which apparently can be better optimized for high efficiency at a steady power output if it doesn't have to provide high peak power for acceleration, since that's augmented by the battery and electric motor.

 

To highlight the problem:


Hybrid Mileage Comes Up Short

Hybrid cars are hot, but not as hot as their owners, who complain that their gas mileage hasn't come close to well-advertised estimates.
Don't knock the car companies for inflated claims: Experts say the blame lies with the 19-year-old EPA fuel-efficiency test that overstates hybrid performance.

Pete Blackshaw was so excited about getting a hybrid gasoline-electric car that he had his wife videotape the trip to the Honda dealership to pick up his Civic Hybrid. The enthusiastic owner ordered a customized license plate with "MO MILES" on it, and started a blog about his new hybrid lifestyle.

But after a few months of commuting to his job in Cincinnati, Blackshaw's hybrid euphoria vanished as his car's odometer revealed that the gas mileage he was hoping for was only a pipe dream. Honda's Civic Hybrid is rated by the EPA to get 47 miles per gallon in the city, and 48 mpg on the highway. After nearly 1,000 miles of mostly city driving, Blackshaw was getting 31.4 mpg.

His story has been echoed dozens of times online by owners of the Honda Civic Hybrid and Toyota Prius.

Data from independent product-testing organization Consumer Reports indicates that hybrid cars get less than 60 percent of EPA estimates while navigating city streets. In Consumer Reports' real-world driving test, the Civic Hybrid averaged 26 mpg in the city, while the Toyota Prius averaged 35 mpg, much less than their respective EPA estimates of 47 and 60 mpg.

http://www.wired.com/cars/energy/news/2004/05/63413?currentPage=all

 

It's rather interesting that the freeway driving gas mileage of a hybrid can be significantly higher than that of a similar non-hybrid since all the energy is being provided by the gas engine under those conditions in either case. The difference must be a more efficient gas engine in the hybrid (which is often an Atkinson cycle type) which apparently can be better optimized for high efficiency at a steady power output if it doesn't have to provide high peak power for acceleration, since that's augmented by the battery and electric motor.

Exactamundo. The engine in the Prius C, for example, is basically the same as in the Yarus. But is tuned to run very effeciently in a very narrow power band, and the electric drives make up the difference when accelerating and hill climbing.

 

the median value on the graph below is about 47 mpg for 2278 cars reported. That's very good, but it's not 55.

55 MPG is for a 2013 Prius at highway speeds. The 47-48MPG is about right for a sampling of Prius models and combined driving. Still way out in front of any all gas car.

 

The difference must be a more efficient gas engine in the hybrid (which is often an Atkinson cycle type)

Can you give a reference to this information?

 

The EPA testing is not real world driving. It is, or was done on a chassis dynamometer. This is so all makes/manufacturers use the same test routine.

 

Sorry if I missed it while scanning this thread, but has energy recovery from waste heat been discussed? Allowing a hot engine to cool to ambient is pretty wasteful.

I've read about thermoelectric recovery, which is less than 5% efficient but is pretty easy to implement. Also read about folks using a liquid coolant to store engine heat in a "thermos". Sounds like a really good idea for cars that need to start at -20°F.

 

With a parallel hybrid like the Prius once it is at a constant speed on the freeway the hybrid electrics are in a steady state (not charging or discharging) and do not increase the fuel efficiency! In a steady state of speed along a flat freeway all the motive power comes entirely from the gas engine, so it's just a gas powered car like any other.

So that same freeway fuel efficiency can be achieved identically from a non-hybrid vehicle, provided it has the same engine, air drag, weight, rolling drag etc. (Actually the non-hybrid would have an advantage that it is not carrying the weight of electric motor and batteries.)

It's a bit silly quantifying the hybrid's performance based on freeway travel. The weight of all that hybrid gadgetry pays back in city driving where the battery can assist in constant repeated acceleration, and in regeneratve braking. Ie; in slow start-stop city traffic.

I can't confirm what was said earlier about possible Atkinson cycle engine, I just don't know. But I think the CVT can let the car cruise at highway speed at an RPM that it closer to its most efficient RPM. But other cars have CVTs and can't get the same mileage as the prius. There IS something about it that makes it more efficient, even at highway speeds. Whether or not we can credit that to the electrics, I don't know. But I do get what you're saying about the steady state, and I agree, at steady state, all the power comes from the engine. Actually, all power comes from the engine all the time, in any hybrid. But I think that the series hybrid I described could still outperform a gas engine car at highway speed, because it would be running perhaps a 2cylinder engine intermittently, always in its power band, while the 4 cylinder competitor would be running continuously, outside its power band. How the prius beats the competitor, I don't know, magic?

 

The 47-48MPG is about right for a sampling of Prius models and combined driving. Still way out in front of any all gas car.

I guess you skipped the other posts:

I drive a 2007 Prius touring model and have been keeping detailed accurate records from time i bought the car new. i have both MPG per the car display as well as MPG gas Pump average. I live in Seattle WA, drive on some hills, do mostly in-city short trip driving and some occasional highway driving. My average gas milage per the gas pump calculation for the over 6 years I have been driving the car is 40.8 MPG, and for the car's display average calculation, it is 39.96.

Like I said: yeah, hybrids get better gas mileage than gas only but they get WAY less than the claims made. The original Prius was rated at 60 mpg city.

The point is: when buying hybrids (at least around here) they were about $3k - $4k pricier than an essentially identical gas car which probably averages 40 mpg highway (maybe 30 city), and dealers were slapping on $3k - $5k mark ups onto the hybrids for the fools who would pay that too. So if you tell me my hybrid is going to get 48 mpg, I am rechecking why I would buy one because the math doesn't work. And the city mileage on hybrids was even farther below EPA estimates.

Basically, hybrids are not economically feasible without the government subsidies (ie, corporate welfare) to support them until gas gets a lot more expensive (like $8/gallon).

I just think they ought to stop lying about the mileage.

And I would force ALL car makers to publish estimated fuel cost per ten thousand miles based on the mileage numbers so people could actually see side-by-side "savings". Most people can not do math in their heads.

AT $4 PER GALLON:

The 48 mpg hybrid's fuel cost per 10k miles is $833.

Thw 38 mpg all gas subcompact is 1052.

SAVINGS GRAND TOTAL = $219 per 10k miles

This is about two cents per mile.

When you consider that the "per mile" cost of any new car that costs about $25k is going to be something like 30 - 40 cents per mile over the first four years of its life (factoring in depreciation, insurance, maintenance, etc) that two cents per mile doesn't loom quite so large.

 

Can you give a reference to this information?

Here are a few references for the Prius Atkinson cycle engine.

 

One thing to note when comparing gas mileage between hybrids and regular cars is the size of the car. A Prius has significantly more interior room (particularly cargo capacity) than many of the super-economy small cars that have near comparable highway MPH (but not city).

And considering that many of us drive more city miles than highway (or slow freeway miles due to congestion) that I think city MPH is likely more important than highway for many car owners.

 

I guess you skipped the other posts:

Like I said: yeah, hybrids get better gas mileage than gas only but they get WAY less than the claims made. The original Prius was rated at 60 mpg city.

The point is: when buying hybrids (at least around here) they were about $3k - $4k pricier than an essentially identical gas car which probably averages 40 mpg highway (maybe 30 city), and dealers were slapping on $3k - $5k mark ups onto the hybrids for the fools who would pay that too. So if you tell me my hybrid is going to get 48 mpg, I am rechecking why I would buy one because the math doesn't work. And the city mileage on hybrids was even farther below EPA estimates.

Basically, hybrids are not economically feasible without the government subsidies (ie, corporate welfare) to support them until gas gets a lot more expensive (like $8/gallon).

I just think they ought to stop lying about the mileage.

And I would force ALL car makers to publish estimated fuel cost per ten thousand miles based on the mileage numbers so people could actually see side-by-side "savings". Most people can not do math in their heads.

AT $4 PER GALLON:

The 48 mpg hybrid's fuel cost per 10k miles is $833.

Thw 38 mpg all gas subcompact is 1052.

SAVINGS GRAND TOTAL = $219 per 10k miles

This is about two cents per mile.

When you consider that the "per mile" cost of any new car that costs about $25k is going to be something like 30 - 40 cents per mile over the first four years of its life (factoring in depreciation, insurance, maintenance, etc) that two cents per mile doesn't loom quite so large.

Your math is close to what I came up too, before I started car shopping. The models which come in a regular and a hybrid version, the non-hybrid is always the more economical choice. I was against hybrids, and FOR small all-gas high mileage compacts. It wasn't until I started going and seeing these cars in person that the prius started to become a viable option. None of the compacts very few of the full size sedans have as much cargo room (very important to me in my line of work); it has more room than a lot of the new SUVs, and ALL of the new micro SUVs (kia soul, Nissan cube, juke, etc).

And for the record, the numbers posted thus far about how bad mileage people are getting are not what I have observed. I bought mine used, with 35k miles on it, and I get 45-49mpg driving normally, mix of highway and city, not paying any attention to the eco meter, with my cargo area full of tools. Some people just don't know how to drive. I know, because I share the road with them.

 

Thank you. I never heard of their VVT-i called "Atkinson" before. A true Atkinson engine uses a totally different arrangement. Crankshaft at half speed and valves operated from the cranshaft
http://www.motor.com/article.asp?article_ID=1729