Mileage hit vs Prius is too severe

Re: Milege hit vs Prius is too severe

http://www.caranddriver.com/reviews/2012-toyota-prius-v-first-drive-review-car-and-driver

Yes, even in a CVT changing the final drive ratio will change the RPM output of the car at a given steady speed, and thus would result in higher fuel consumption. And they did change it as reviewers have stated, for performance reasons. It is also probably true that it is more efficient vs the standard Prius ratio from a "bang for your buck" perspective in the v.

From a straight absolute standpoint though, there will always be some sort of MPG penalty for increasing the ratio within reason; you can't work around that.

 

^ Thanks!

I couldn't quickly find the reference and had other higher priority items. I knew it was mentioned around launch time and was brought up during my test drive at GDE. With the above ratio, I quickly found other articles that mention the same thing like 2012 Toyota Prius V Full Test and Video and Review: 2012 Toyota Prius v | The Truth About Cars.

 

Just the Cd differences of 0.29 for the 'V' and 0.25 for the Prius is 16%. At sane highway speeds air friction is about 50% of total resistance, so the Cd difference is 8% fuel consumption increase. Drive faster, and the penalty will increase more.

 

Re: Milege hit vs Prius is too severe

The air friction story is worse than that. It is the Cd*A product that matters, not Cd alone. The 'V' increased both.

I understand why the drive ratio changes acceleration performance. The ICE is not allowed to produce full power until the system builds up some speed. The ratio change allows it to reach full power quicker.

But I don't understand why drive ratio alone, absent the changes in weight and air drag, should have any first-order effect on fuel economy in the HSD. Your link and Cwerdna's links give no reason why, or anything at all to distinguish the comments from held over conventional wisdom about convention powertrains.

I can imagine second-order effects, such as the change in power split changing the energy conversion efficiency of the electric path through the HSD. But this should be very small compared the first-order pumping loss changes in conventional systems.

 

I don't understand why OP is surprised about the mileage difference. A Prius v is bigger, taller, wider and longer. As far as I concerned, not the same vehicle, yet every Prius from now on is expected to hit 50mpg regardless of size of the vehicle, and its wheel/tire sizes.

Cwerdna put the best explanations and references, I look at it in terms of %. I am looking at the 2012 Camry Hybrid XLE vs. Camry Hybrid LE and willing to loose a little bit of mpg for those 17" wheels.

A BMW 328i vs. 528i with the same powertrain(3.0), has about the same 9% mileage difference of the Prius v vs. Prius.

 

So what will happen when CX-5 goes on sale next spring? cheaper, lighter, better hwy MPG?

 

We'll see what the real numbers are, but I bet it wont compete in the city and overall. Also, the cx-5 looks like it will have small capacity.

 

Keep in mind that even the addition of 17" wheels can drop the Prius mpg by 6 or more.....

AlsoKeep in mind that the GenII was only rated at 46mpg and it was much smaller than the v.

 

More than that, according to the PC folks lucky enough to talk to the engineers during pre-release meetings a few years ago.

The 'v' does have a larger cross-section (4.1 inches taller) and a worse Cd in order to get a significantly larger interior volume (15.7 cubic feet extra) compared to the Camry. These cause significantly more air drag than the Camry faces.

 

Suppose the Prius c landed first with 58mpg and later they introduced the bigger, taller, longer, wider, heavier current Prius with 50mpg. Its 50mpg would have been seen by some as a severe hit, and because every Prius regardless of size would be expected to get 58mpg?

 

Yes. The V trim Prius does get worse mpg than the lower trim models with 15" wheels. Don't let the EPA number fool you. The EPA did not test the V model equipped with 17" wheels.

 

worse? yes. how much worse? depends on how you drive, but certainly not 6mpg worse. I have the 17" on my Prius 5 but I get 49-50mpg overall. Considering I do mainly highway (85/15 highway/city) I am actually meeting EPA estimates. Of course if I had the 15" wheels I may be able to easily beat EPA.

If I recall correctly people have generally found a 3-5% decrease in mpg to go to the 17" wheels.

 

Nothing.

MazdaUSA - Inside Mazda - Auto Shows

SKYACTIV® POWERTRAIN
Mazda creates a new-generation automatic transmission that achieves excellent torque transfer efficiencies. The result? An improvement in fuel economy of up to seven percent compared to current transmissions.

What is a 7 percent FE increase going to do against the Prius v ?

Nothing. Mazda - tier 2 or 3 or whatever company. They can't touch Toyota.

CX-5 looks like a brick with lots of drag anyway.

 

I think introducing Prius c first would have been a mistake.

thee top selling cars are -

Camry, Fusion, Accord, Altima, Sonata, Corolla, Civic, CR-V ....

the vast majority of them are conventional cars. Most of them average under 30 MPG. The average American does not squeal over a $120 / month gasoline bill. Many at Priuschat do. But most Americans don't spend their time posting on Priuschat.

Advanced technology cars have to be made very, very well to compete with the top selling cars. Consumers want very few compromises. They want space, they want enough power, they want all sorts of features, good looks, everything and at a decent price. Most do not want smaller cars that they don't have a prayer of getting their family of 5 into (i.e. Prius c). Mazda 2's, Fiestas, etc are niche cars.

Camry hybrid. It sells ok, but most opt for the regular Camry. Maybe the 2012 will gain ground.

In a way, Prius v is kinda sort of like a Camry hybrid, but with a hatchback. Some people like hatchbacks. Some will see the added functionality of the hatchback. Prius v looks every bit like a family car.

I am a little bit concerned about the power output of Prius v and how it will do when loaded to gills heading up the mountain on vacation.

 

Go stick a set of OEM 15" wheels on your car and go do some testing then get back to me.

I've done more testing between 15" and 17" wheels than anyone I know and the results are always the same regardless of the tires. Can you point out specific threads or posts where someone has performed similar tests over a similar length of time or number of tanks in a Geniii? I'd be particularly interested in seeing such a test in reverse using a Prius V with 15" wheels instead of their OEM 17s.

Just because you meet EPA ratings with your V doesn't mean you wouldn't acheive much higher mpg with smaller wheels. Hell I meet EPA highway (45mpg) rating with my 17s too but I can acheive 6 mpg more with the 15s and much higher if I actually try. Driving style, environmental conditions, and a host of other factors come into play when determining average mpg but after 5 yrs of swapping wheels and 5 different tires the effect is always the same. Others who have swapped wheels and made careful observations noticed a 4-6mpg loss on average with the Genii. The Geniii may be affected less due to higher TQ rating but there is no way you will only lose 1mpg with such a swap.

AllI can say is that until someone contradicts me with more conclusive data than the typical half-assed guess or careless observation I will stick to my observations and opinions on the mpg loss when upsizing wheels and tires.

 

I could see your point because every time I drive the 3rd gen Prius with the 15" wheels (3 or 4), the MPG average is way over 50. Last time I dropped it off reading about 55 on gage, 60 at pump. Time before about 57 on gage, 59 at pump. This is mixed driving lightly loaded. Every time it just slams the epa numbers. I always check the tires before heading out and half the time I'm in power mode. I driver fairly easy though.

 

I was comparing to EPA, not to what I could achieve. Perhaps I could get 6mpg higher if I had 15". But you made it sound like that the Prius 5 would get 6mpg less compared to the EPA with the 17". (44mpg? haha no). And I never said the drop was only 1mpg.

The only frame of reference that I have for such a comparison was a co-worker who drove a similar route to work as me but had a Prius III. She got 58-60ish mpg (according to the MFD), but then again she drove 55mph on the highway. If I did something similar I could achieve pretty close numbers (I tried that once, but it drove me nuts going so slow).

I do await someone who has actually done the swap to come back with numbers as well for the 2010 Prius.