Prius Newb Arises!

The power outlets are off when the car is off.

 

This improves mpg compared to the placard pressures, but no specific safe pressure will maximize it. Tire pressure is a compromise among several conflicting goals, e.g. mpg, comfort, handling, comfort, tread life, traction, and comfort.

I hope the dealer did not tell you that the 2010 has a fuel bladder, because it does not.

This car has fantastic fuel range, so I don't worry about how to maximize the fuel refill.

 

Welcome aboard!

I'm not a hypermiler, so my opinions (and they ARE just that) are somewhat prejudiced, but you may be over thinking things just a bit with the gasoline fill up. You never want to overfill the fuel tank. Just going to the first click is always good practice in any car, and the Prius is probably equipped with some kind of evaporative containment system---and I'm sure it's some kind of Rube Goldberg inspired series of solenoids tubing and sensors that aren't well equipped to deal with fluids rather than vapors. Just a guess, but the extra .25 gallons of fuel aren't worth it even if it just spills out onto the pavement.
I'm pretty sure that the fuel that you buy comes from a big tank, and it's probably underground. This means that the fuel inside is pretty temperature stable. Even if the tank is above ground, the thermal inertia of the petrol inside is going to enure that you get pretty much 1.0000000 gallons of fluid instead of the 1.0000001 that you're hoping for.
We use 500-5000 fuel tanks in the telephone industry (for backup power,) and they're monitored by these gollywog systems that account for Temperature, Humidity, Pressure, who won last night's episode of 'Dancing with the Stars" etc... I'll see about a 1 gallon delta in a 5000 gallon exposed tank---and most of this is due to noise in the measuring system.

Tires are another matter altogether! You don't haul kids around in your car---do you? Ford Motors learned a very expensive lesson in what happens when you tinker with tire pressure settings. Granted---they went the other way, but I'm pretty sure that if you run your tires at 40psi instead of what the manufacturer recommends, then you're going to change the handling characteristics of this car---and we're already dealing with a car that isn't well renowned for its ability to turn on a dime and give you nine centavos for change---if you know what I mean.
An overinflated tire is stiffer than a "properly" inflated one, and while I'm sure that the extra 6-8 psi isn't going to turn this little car into a death trap, you need to be aware that Toyota didn't just pick a number out of the ether when they recommended tire pressures for this car.
You're probably not going to get into trouble by bumping the pressure to 40, because one advantage of living in a society populated by a sprinkling of bed-wetting, sniveling attorneys, is that manufacturers have a powerful incentive to make it harder for people to hurt themselves.

I'm not trying to take the fun out of tinkering with your new toy...far from it! You just need to be aware that even something as noble as saving the planet can be overdone.
Example: Drafting.
Example: Creeping away from an intersection at 5mph during rush hour traffic.
Example: Thinking that if you overinflate your tires by 8psi is GOOD...then doing so by 16psi is BETTER!

Have fun!
Experiment!!!!

Welcome to the sharp end!

 

No bladder in the 2010. I'd keep the pressures up, but maintain the required 2 psi differential front to back. 42/40, or 40/38.

 

Overinflated tires (up to the allowed max pressure posted on tire) produces the following:
better fuel efficiency
better handling via decreased sidewall flexing
lower tire wear
better traction in ice/snow
less comfortable ride
possibly uneven tire wear (more in center)
worse traction in mud/sand
possibly increased rate of puncture (theoretical)

This is not just opinion, but studies-proven facts.

As for the recommended PSI Toyota arrived at? The standard industry calculation dividing car weight + margin of safety per tire vs max tire load and applying the percentage to the max tire pressure. This number is not specifically tweaked by Toyota for handling, MPG etc. Ford problem was they used too little margin of safety in their calculation, tweaked the number toward comfort of ride and then used tires that did not well tolerate user abuse (ie riding on under inflated tires).

 

To call a bluff:

I want to see the studies proving more center wear, for modern steel belted radial passenger car tires. Nearly everything I see indicates this vanished along with the old bias ply tires.

 

[:welcome:

 

My understanding is the different modes are mainly accelerator pedal mapping: PWR most sensitive, ECO least sensitive. ECO will also reduce a/c loads too but this time of year even in FL you probably won't notice it. The engine doesn't make any more HP in pwr mode. EV is pure electric mode, has many limitations, and won't engage if beyond those limits; think parking lot or, better yet, parking garage use.

40 PSI is well within the tire specs.

Use the HSI panel display and try to keep max acceleration in the main part of the display (ECO zone) but just out of the PWR zone (if traffic permits). Read up on Pulse and Glide (P&G) techniques for the ultimate mpg. Surf the Gen III fuel economy forum for tons of info on FE.

:welcome: to PC.

 

EV mode is Electric Vehicle Mode. This mode has many variables such as it will only engage if you have 3+ bars on the traction battery AND engine temp 68 degrees or above. It has a max speed of 25 MPH (10 MPH until the motor is warmed up) and is generally used to move short distances, like in a parking lot or backing out of the garage. It will auto over ride to the ICE anytime it is not within EV specs, eg., to cold or exceeding the speed limits of EV mode.

As far as changing modes for your drive home, it's totally a matter of taste. The Power, normal (default), and Eco modes, as earlier said, simply map the responsiveness of the accelerator pedal. Try this, on the freeway set the CC and watch for speed variance when climbing a hill. In Eco mode with CC set at say 60 MPH, when starting up a hill, you may see up to 2-3 MPH drop before the CC starts accelerating. In normal mode, that same hill at 60 will see a drop of only 1 MPH and in Power mode, no change in speed. It's all simply a matter of responsiveness.
:welcome:
Before someone correctly corrects me, Eco mode also regulates power draw for heating and AC and I believe it will allow the ICE to stop running if all it's being used for is to heat or cool when the car is at a stop.

 

Do a google search if you don't believe it.

I personally mildly overinflate tires (~40PSI) in my cars and don't see abnormal wear. The opposite, when I used stock pressures, I had more shoulder wear in my cars. Higher pressure mitigated it.

Once I bought an used car from my friend with bold centers in front tires. I checked pressure and he had 50+ PSI. Apparently he never checked his pressure and the tires were overinflated while mounted some 20000 ago (he did a lot of Hwy driving).

 

re gassing up: I second the other poster's advice not to overfill, and, regarding the amount of gas you can fit in, the time of day doesn't matter a bit (if it did, you'd be better off gassing up at the crack of dawn, or whenever it is cold). The only advice about the time of day I'd give is, if you can, late in the day or after dark, for air quality purposes--so the VOCs and such emitted during any fueling process don't have time to cook in the sun and add to ground-level ozone pollution.
~T

 

OK...I'll buy some of that...but why then would Toyota want to cheat you out of the 1-3MPG that you gain simply by goosing the tire pressure by 6-8-psi in a car that they sell to get crazy good fuel economy? Why would they take a car that already sacrifices so much in the way of comfort, upfront cost of ownership, and other areas and throw away such an obviously easy 5-percent gain in efficiency by telling you to under inflate your tires?

In engineering you always give something to get something. Stiffer tires handle better in SOME situations, but you actually want (just)a little sidewall flex in a skinny 15" tire for certain handling situations....

My needs will be a different in this car than other drivers. I never carry a passenger (not allowed to), and my driving is monitored by a self-insured Fortune 50 company so I take it pretty easy, and the biggest load that I will carry in this car besides my 175# bulk is about 50-pounds worth of tools and test equipment---so yes, besides the aforementioned monitoring by "Big Bell" I could probably squeeze another 10# of air in the tires and be just fine. It's not like the ride quality is going to suffer that much...

But the little red light flashing on my fecal detector tells me that Toyota Iron Works didn't just pull a number out of their stern and paste it on the door jam to deprive everybody but those reeeeallly smart people (or worse---people who just THINK they're smarter than automotive engineers!) who can see past their skullduggery and avail themselves of the 1-3 MPG that's rightfully theirs...

I do not know....call me a skeptic. I might just have to sneak a few puffs of air into my tires when AT&T isn't looking and see if the "dizzy-whizz" tells me that I'm getting over on the man....I’ll let you know.

 

Wrong. They don't tell you to underinflate tires. They tell you to inflate to pressure mandated by the tire engineer, who is independent from the car engineer.

Yes, that sidewall flex is for better comfort on bumpy rode. We covered that.

You are funny, but there is more to the tire pressure that you think you know.

Like I said before, Toyota did not a make up a number for PSI in tires.
They went by the numbers tire engineer calculated based on car load and max load carring of the given tire size/construction. In case you didn't know (and looks like you didn't), the tire industry is highly regulated and by laws the max load carrying in US passanger tires is capped at 35 PSI, even though the modern passanger tires are capable to safely withhold cold pressures of 44 PSI and even 51 PSI (check rating on your own tires). This limits the PSI car makers can legally recommend in US.

 

So...what you're saying...in a "friendly" way to be sure, is that Toyota would "like" to be able to tell us not to underinflate our tires, but the oppressive DOT regulators will not allow them to "recommend" OEM pressures of greater than 35-psi.
So before the ink is dry on the purchase order for our new car, we should run and not walk to the nearest air compressor and shoot the pressure up to 40-psi?
Right?
Hmmmm....sorry. My truck tires are direct replacement for those found on nearly all full sized pickup trucks, which probably carry OEM inflation recommendations from each factory (I didn't look) that are pretty close to the same---since your basic Mk-1, Mod-0, 1/2-ton pickup truck is the same basic critter, with the same basic handling characteristics.

However (comma) this tire, which is the same round black rubbery tire will also fit onto an Escalade...or a Highlander...or other vehicles with differing centers of gravity, weight, springs, radio antennae, ect...which "probably" (didn't look that up either...) carry inflation recommendations that are a little different...for the same tire, as determined by the vehicle manufacturer---not the tire manufacturer, who has no earthly idea which vehicle his or her tire will be bolted onto.

This is why everywhere you look, besides Prius and certain motorcycle forums, they always tell you that you should follow the vehicle manufacturer recommendations, not the number that's printed on the sidewall of the tire, or what your neighbor says, or what wise butts like me say.

Should.
Not have to.
Should.

 

RE: Acceleration

Don't mash the pedal. Don't crawl from a stop. Speed up to speed "smartly"... quick, but not peeling out. Ease off to maintain desired speed. The real secret to better fuel economy is to minimize brake usage. In other words, look ahead. Look at the cars in front of the car in front of you. Anticipate traffic, lights, and turns. This is how I have always gotten better MPGs, no matter what vehicle I drive. It works well in the Prius, too.

 

Thanks for admitting that you don't have it.

If it was real, multiple years of reading tire pressure wars in PriusChat and CleanMPG.com ought to have revealed it