Are all Prii created unequal?

We have 2 Priuses an 05 and an 06. My 05 gets on average 6 mpg better mileage then my 06. The difference? Well, my 05 commutes 30 miles one way mostly level and on the freeway. I commute 30 miles both ways through combined city and freeway and I go over a 1600 foot climb each way. The 06 has only 7800 miles on it while the 05 has over 20,000 miles. No matter what I do, I can't come close to her 45 in winter and 55 summer averages. My averages right now are 39 winter 47 summer.
Paul R. Haller

 

Does your wife have a short commute as well? The Prius does not do as well with short trips, other ideas are is your oil overfilled (best at midway between add and full), what weight oil are you using? Also check the alignment and try pulse and glide between 33 and 40 mph, this is the key to great mileage. Also in warmer weather your mileage will improve. Blocking the grill so the ice stays warmer in winter also helps.

 

I can offer one potential explanation on the Prius vs. HCH thing.

The bread and butter of fuel economy in a Prius is speeds below the 42mph threshold where the ICE is forced to remain on all the time due to the limitations of the power split device. Under perfectly ideal conditions (flat roads, warm weather, and absolutely no traffic) a truly skilled driver can pulse and glide to triple-digit fuel economy. Of course you could never expect that in the real world, as it's a theoretical maximum. Above that speed the Prius starts falling down because the ICE can't truly shut off and there are some (though I think very, very small) energy losses while HSD converts some energy from mechanical to electrical and then back to mechanical while maintaining the super-tall gear ratios on the highway. You can get fantastic mileage, yes. Just not as fantastic as at low speeds.

The HCH is a different beast entirely. Does she happen to drive a 5-speed version? Those are fuel economy monsters when allowed to cruise at anything from 40-60mph. The reason is that the manual transmission Civic employs a lean burn at low engine load, dramatically improving engine efficiency. It also drives the wheels directly through a tall gearbox which I believe to be of some benefit vs. HSD. The CVT version doesn't have the benefit of lean burn, which levels the playing field quite a bit. But it still has the benefit of driving the wheels directly at a very high gear ratio. On the other hand, the Civic can't keep up with a Prius at those low speeds where HSD allows for all kinds of gliding and stealthing.

So it really comes down to two different cars that really shine under a different set of conditions. It could be that her driving cycle favors the Civic's strengths more than yours favors the Prius's strengths.

 

<div class='quotetop'>QUOTE(notperfectlyclean @ Jan 13 2007, 02:48 PM) [snapback]375210[/snapback]</div>

swap cars for a month and see how the numbers look.

different cars, different routes, different drivers, different traffic patterns.

lots of variables.

 

<div class='quotetop'>QUOTE(Paul R. Haller @ Jan 13 2007, 03:04 PM) [snapback]375215[/snapback]</div>

We also have 2 Priuses, with the same problem. I have an 04 with 40k and she has an o6 with 10k. I average 4 to 5 mpg more than her and attributed it to her driving habits or tire pressure at first. Last month we tried an experiment on a 60 mile roundtrip caravan into downtown Phoenix. This was with the same tire pressure, gas reset, route, ambient temperature, payload, etc. Results were 49.8 vs 44.7 on the MFD verified closely with a tank refill when 8 gallons were required. The dealer's tech checked the car and said not significant! They are supposed to setup a meeting with the district Toyota rep, but we'll see. I don't see how you can set up a better experiment than the one we did, actually gassing up and tailing each other for sixty miles. :angry:

Arnie

 

<div class='quotetop'>QUOTE(arniesalsared @ Feb 4 2007, 11:46 AM) [snapback]385197[/snapback]</div>

Switch cars for a few days and see if the fuel consumption changes for better or for worse, in one or both cars. Just because she followed you does not mean that her driving technique was as conducive to fuel efficiency as yours. She could have still been pressing the accelerator in situations where you were already coasting and then making up for it by using the brakes more than you did. Based on my almost 30,000 miles experience, high mileage benefits from anticipation.

 

Besides all the tire and driver and road and weather and trip length considerations, Prius mpg can be reduced by poor suspension alignment (toe-in) and maladjusted friction brakes. The latter two can be easily addressed, and may serve to make Prius unequal.

 

Well, I know on my '02 Prius that I rarely got below 50 MPG, and that was only when it was freezing or lower outside. Actually 47 MPG has been the lowest I've ever gotten, and I'm a delivery person so my trips are very short. In the summer I can get about 60MPG, depending on how I drive. I tried the blocking radiator thing and it works pretty well for me, getting almost 53 MPG when I was at about 49 MPG before, and it's still going up for me. Also, I have my oil overfilled as well. I'm gonna have to go drain some of that as well. It's about a quarter inch over just like the other guy. Guess that stupid people at Walmart can't figure out when they've put enough oil in. I will say the dipstick is in a weird place as it took me a while to find it.

I'll see if my mileage improves when I remove a little bit of oil.

I guess it just depends on the driver. I do consider myself a pretty conservative driver on my Prius, not like on my old Isuzu. On my old car I'd pretty much floor it everywhere because it didn't really have an affect on my MPG. It did a little bit, maybe 1-2 MPG, but not like 10MPG or more on my Prius.