What is mpg at 78-80 mph?

[Lord_Towers]

i just finished a trip from SF to a little below LA, on the way down i was driving 80-90 on I-5 with a few bursts of over 100, and the way back it was 70-85 average

MPG down: 46.6
MPG up: 47.7

[KTPhil]

From:
The Prius's Not So Secret Gas-Mileage Secrets - All About Prius

"The Atkinson cycle has a longer power stroke than compression stroke, which enables the engine to produce more power in a certain operating range. The 12- to 14-percent gain in efficiency versus an Otto-cycle engine is mainly due to the reduction in pumping losses, or the amount of energy needed simply to suck air into the cylinders and then expel spent exhaust gases.
Toyota's use of a electronic continuously variable transmission--it uses a planetary gear set to vary the power split among the engine, primary, and secondary electric motors, instead of a fixed set of gears-- allows the engine to stay in its high-revving efficiency sweet spot for greater amounts of time than it would with a traditional, geared transmission."

What these two statements imply is that the advantage of the Atkinson engine is gained at the higher rpm ranges. Therefore I agree that even at high rpms there is a residual advantage to a Prius over a similar Otto-engined Corolla.

The real advantage of the Prius is in City mileage where the CVT effectively keeps the engine in the optimum rpm band. Another example of "synergy."

[drees]

Originally Posted by KTPhil

Once you are up to high freeway speed, the advantage of the hybrid drop dramatically. At those speeds you are not using the electric portion of the drivetrain to any significant degree, and you are on gas power alone. I would be surprised if the "hybrid premium" is overtaken by fuel economy at those speeds. If you need economy, get a loaded Corolla.

BS - what other mid-size gas burning car gets 40mpg+ at 75-80mph?

THERE AREN'T ANY

[KTPhil]

Originally Posted by drees

BS - what other mid-size gas burning car gets 40mpg+ at 75-80mph?

THERE AREN'T ANY

You miss the point. The several thousand dollar premium for the Prius will not be paid back by the slightly lower FE of another economy car. Economy is related to total life cycle cost, not just cents per mile.

[Spin359]

I go back and forth 400 miles quite often, and I get an average of 42 when i'm traveling at 85 on the interstate.

[KTPhil]

Some quick figures, all subject to variation, but you'll get the point.

MSRP of Corolla ($15,250 - 18,760) vs. Prius (23,375 - 24,270), gives an average difference of $6817.

Difference in gas costs for Corolla (35mpg) vs. Prius (48mph) on the highway, at $2.25 per gallon, and 40,000 miles per year... works out to $696 per year.

At this rate, it will take 10 years (even ignoring interest expense) for the Prius to pay back based on highway gas savings. Your Prius will be pretty worn out at 400,000 miles (as would the Corolla), so the difference in trade-in value (one of the reasons for the Prius' low TOC figures in trade magazines) is not a factor.

I'm not equating the cars, but I am being realistic about the cost per mile difference that the Prius gives for you, since that seems to be your criterion for car selection... and the cost to obtain it.

No BS.

[bwilson4web]

Instead of answering the original question, the thread drift has now wandered into a vehicle comparison by proposing the Corolla as a substitute for a Prius. Often called a 'red herring," this is a familar game since until about six months ago, the Corolla was the standard comparison vehicle of hybrid skeptics.

So if we play this game by 'the rules' (per the Boston Globe), we also get to choose whatever price source we want. For example, Edmunds, Consumer Reports or my favorite, the Manufacturer Suggested Retail Price (MSRP) without regard to any other vehicle attribute. For example, an average of MSRP prices or any other criteria that supports the claim. Done properly, we can just grab any price or model combination or options combination that supports whatever claim we want. So playing by 'the rules', I choose the lowest MSRP found for each vehicle at the manufacturer's web site. But remember, the Corolla lost its cache with the hybrid skeptics about six months ago.

The EPA web site, www.fueleconomy.gov, classifies vehicles by "Market Class." Sad to say, comparing a Corolla to a Prius jumps between two Market Classes, "Family Size Sedans" and "Small Cars." A proper comparision would at least choose vehicles within the same market class or if from different market classes, the least expensive ones. Cool, this will be fun:

FAMILY SIZE SEDANS

EPA Hwy	Combined	Make	Model	MSRP
45	46	Toyota	Prius	$22,000
34	34	Toyota	Camry Hybrid	$26,150
34	29	Chevrolet	Malibu Hybrid	$26,225
34	29	Saturn	Aura Hybrid	$27,045

Sad to say but if the original poster wants a fuel efficient, family sized sedan, to compare with the Prius, they will have to go with the less expensive Prius and . . . get the best mileage. They can pay more and get less mileage in the EPA Family Size Sedans.

SMALL CARS

EPA Hwy	Combined	Make	Model	MSRP
45	42	Honda	Civic Hybrid	$23,650
40	33	Volkswagen	Jetta Diesel	$22,270 (manual)
36	32	Toyota	Yaris	$12,205 (manual)
37	32	Mini	Cooper	$19,200 (manual)

Sorry but the Corolla showed up as fifth, not in the top four mileage in either class of car. But not to worry, the Toyota Yaris did and it is even cheaper than the proposed Corolla.

The original poster will love the Yaris, a great commuting car with better highway mileage than the Corolla. Yes, quality counts and the Yaris is another Toyota. The original poster will have a lot of fun at 80 mph on an icy, snow covered highway where the Yaris makes the drive so entertaining. Not to worry, the original poster can count on the terrific savings, nearly $10,000.

Yes, like "KTPhil" points out, the original poster can save a bundle by just taking a less expensive car in the next smaller group. Don't save $7,000 but rather $10,000 with the Yaris. Now if the original poster will soften up the mileage requirement, I understand there is an even cheaper Kia. Too bad the Yogo is no longer for sale except in the used market.

Now if original poster is willing to jump vehicle classes, they can also jump into the used market, which includes my favorite, the GEO Metro, a really fun car. Experience the thrill of a motorcycle sidecar sandwiched between two motorcycles. Indeed, the new GEO Metro owner can probably get one for $2,000 and save $20,000.

Of course the original question was "What is mpg at 78-80 mph?" and that is a fine question. We don't need to substitute other vehicles because there never was a list of original requirements. That is an entirely different question having nothing to do with 'mpg at 78-80 mph.'

Bob Wilson

[KTPhil]

Not really sure what your point is... he stated he drives 40K a year due to a long highway commute, so I used his scenario.

I chose the Corolla becasue you can make a pretty comfortable car out of it if you load it up, and still save thousands over a Prius.

The Prius is a better car for many reasons, but his primary goal was good highway mileage and economy; the latter favors a car other than the Prius. I love mine, but not just for highway mpg (instead, in the Prius I seek room, carrying space, novelty, AT-PZEV, and overall fun and value).

[seesfar]

Originally Posted by destro23

I'm just going to do the math if the extra 6k-8k for a hybrid(over a similar sized/featured car) is worth it for me. Lets say a regular Honda Civic..

i'll do the math and post what i think a little later.

Keep in mind that the Civic is a compact car and the Prius is a mid size car Much more room than a Civic I own both a Prius and Hybrid Civic. Highway MPG at sustained high speed is within 42-45 MPG for both.

[M8s]

Originally Posted by destro23

So what is the mpg at 78-80 mph?

We just drove from AZ to CO (840 miles) with a fair load (3 boxes of files, 2 golf bags, 2 laptops, overnight bag and 2 passengers). We used the cruise control and kept up our speed except for brief stops for gas/food and a short traffic slowdown in ABQ. Here's wat we got:

Mesa AZ to Raton, NM - 45.5 mpg (pretty flat except for the Mogollon Rim and Glorieta Pass, cruise control on 79 and 80 mph, very little wind)

Raton, NM to Lone Tree, CO - 44.3 mpg (pretty flat except for Raton Pass and some miles-long hills, cruise control at 77 and windy in So. CO)

Hope this answers your question. BTW, I used mid-grade gas (89 octane)