2010 Prius III fuel efficiency hypermiling results

It doesn't matter if the TIRES are designed to handle the pressure. Why would you even incorporate that into your thinking about the dynamics of the car?

Do you believe that all that matters is "can the tires take this"?

And you have zero idea if "braking and handling are the same". All you know is YOU haven't found the edge of the envelope YET.

But you aren't testing it for hundreds of thousands of miles under all types of conditions--that is, until you meet one of those conditions that the car SHOULD be able to handle with an average driver.

When it doesn't handle it the way it was designed to, YOU are the sole factor at fault. Not Toyota.

When you hit me, I will take your tire pressures and add them to the police report.

Tire Pressure ========= As some have predicted, I've finally experienced some lost of tire tractrion from the increased tire pressures at 48 psi front and 46 psi rear using Yokohama Avid S33 all season tires that come standard with the 2010 Toyota Prius III. When attempting to go from 35 mph to 0 mph on a wet 10 degrees downhill grade on an asphalt road - the loss of traction added approximately about 20 feet more to the stopping distance. Because I normally start slowing down and braking early ( to maximize energy recovery via the regenerative brakes) I noticed the loss in braking performance early and I was able to easily compensate for the loss of performance. Sadly the

48/46 psi tire setting has not provide any noticeable fuel efficiency improvement than the 44/42 psi setting. I have since reset the tire pressures back to 44/42 psi setting which in the past improved fuel efficiency but still provided adequate level of performance wrt to braking and handling in urban/suburban driving environments..

Grill Blocking =========== The 100% grill blocking has reduced the number of times the Prius turns on the ICE to keep the catalytic converter/emissions system warm. Sofar the coolant temperature has stay more or less under 181 Fahrenheit degrees in mainly urban driving. For the winter, grill blocking has been a significant factor in keeping the FE up. More effective than grill blocking is to just to drive when the temperature is warmer, e.g. drive in the afternoon instead of at night.

2010 Toyota Prius III, Blue Ribbon/Dark Grey, OEM floormats Yokohama Avid S22 (front 44 psi, rear 42 psi) ScangaugeII ( RPM, MPG/AVG, FWT, GPH) lower grill 100% blocked, upper grill 100% blocked DC/MD/VA metro area odeometer = +7500 miles

And one wonders why Toyota engineers didn't do this themselves.

In other words, what are you breaking on your car by doing this.

Nothing so long as you monitor the ICE and inverter temperatures via a Scangauge or similar. When they start to get too hot you simply remove the grille block.

Considering the Avid S33 tires are only 44 max cold rated it is no surprise that overinflation resulted in less traction. To me the pressures on the door jamb sticker are the minimum and the ones on the sidewall are the maximum, kind of like the "add" and "full" marks on an oil dipstick.

I love watching ignorant people speak.

Again, one wonders why Toyota engineers didn't do this themselves. It's quite easy--just do it with the appropriate thermostat, and keep the coolant out of the radiator--out of the airstream--until it gets hotter.

So, the question stands: what are you breaking by doing this. What DON'T you know about your car that the engineers DO know? What expensive tradeoffs are you making in order to play your rolling video game and make a high score appear on the screen?

You're no doubt increasing the total cost of ownership of the car in ways you haven't anticipated, because you're laser focused on one thing and one thing only: fuel mileage. You think that gives you bragging rights.

You're like the guy who throws nitro into his Civic, then blows it up street running against another ricer. You want one thing and one thing only, and you don't care how much money you spend to get it.

It's highly ironic in this case that because you're doing things that the engineers have already decided against, you're causing MORE harm to the environment because your car won't last as long and will require replacement sooner.

Your search for a high number on your rolling video game is harming the environment.

I love watching ignorant people speak.

Do you have a lip fetish? I prefer to listen.

It's not me, I drive a '97 Lumina 3.1 that gets half the MPG of the NHW20 Prius. I do want one with a burning passion though. Requirements are NHW20 model, Seaside Pearl or Millennium Silver color, Smart key (SKS/SE,SS), non Touring, and preferably '05-'07 model year.

And the Prius does have a thermostat on the ICE coolant loop but at 50 MPG it is only burning about 1 gallon per hour and the block itself can dissipate too much heat for it to stay warm.

Methinks they should have installed air shutters in front of the radiators kind of like the old OTR trucks (semis / lorries)

I personally loathe those who forget that the primary purpose of the Prius is low emissions not high MPG. Some are hacking into the wiring for the coolant temp sensor to fake a higher temp for better MPG. This is just straight up wrong. For me it falls right in line with the O2 simulators to fake MPG gains from HHO or eliminate a P0420/P0430 when gutting or removing the catalytic converter.

If you are referring to me please enlighten me where I am wrong.

I have hand mounted everything from ATV tires all the way up to the 38" tires on a John Deere tractor. The inflation has to match the loading, doorjamb is minimum for comfort, sidewall is maximum, and somewhere between is the correct pressure. If you have 80PSI cold rated tires on a full size truck you only need all 80 when you have a load on. For instance the NHW11 Prius was known to edge wear the OE tires at the stock 35/33 pressure. The tires wore evenly at 40/38 and higher.

"Hypermiling" is a game. Some people love to fool themselves playing games.

You would be wrong, but you may continue to think as you wish--until, that is, you cause an accident.

Youthinks so out of ignorance of the entire picture.

You didn't do the engineering, you didn't do the engineering testing. You don't *know* what (to you) unintended consequences come about by blocking the radiator. That's my point. The engineers DO know. If they could have gotten FREE miles with a simple blocking of the radiator, they would have done so.

But nothing in this world comes free, and the engineers no doubt discovered the REAL price the user pays by blocking the radiator. You, on the other hand, don't know the REAL price. All you know is the IMMEDIATE benefit. The long term cost? You aren't even considering that there may be one.

I guess with all those words in all caps, you MUST BE RIGHT. ;-)

More likely Toyota didn't want to spend the extra money, and didn't want to risk the cheapo shutters they would have installed staying closed in warm weather. Since 2007 Toyota seems to have the design goal of "Cheap plastic, everywhere possible."

You are deluded if you think snow and ice traction are unaffected by tire pressure. Make sure you note it in your next accident report, and pay up on contributory negligence.

The "tricks" that we're discussing involve altering the car in ways not intended by the engineers, and not stopping to consider just why the engineers didn't do these "tricks" themselves.

The "tricks" involve assuming that YOU know more about the car and the long term consequences of the "tricks" than do the guys who designed the silly thing. You don't, of course, but you fool yourself into thinking you do, simply because you want to play games to make the glowing number on the dash be higher.

You're playing a rolling video game with one goal in mind, and damn the consequences? That's fooling yourself.