Ignition vs. Roll start?

[Yaris Hilton]

No, you can't roll start an automatic.

[1stToyota]

Originally Posted by Alypuppy

I must say I am impressed that with the Yaris mileage obtaining 40mpg over 1368 miles with a good mix of long freeway driving through New York and Massachusetts on winter fuel and tires. I cannot wait for summer!

However, I have a question. There are a lot of hills in my area and I often find places to cost for over a quarter of a mile. For these I turn of the car and let it roll and am even able to roll into and park my car in the school parking lot after .2 miles of costing and over 360 degrees of turning.

Most of my coasting, though, is when I see a red light in the distance. Sometimes the light turns green and I love the extra mpg boost from not having to start from a full stop, but I would like to know:

--> Which is better? Roll start the car in an appropriate gear? Or use the ignition system to start the car? Also, many say the wear and tear of ignition is similar to 7 seconds of the engine being on, so I turn my car off for nearly every light and am debating about turning off the car to roll up to stop signs... is there too much of a good thing? I do use the fuel shutoff DFCO (sp) as well, but I find I would rather just turn the car off and coast for greater distances.

Also, did I notice that the ODO only counts when the car is actually in the on position? After driving an SUV, the lack of power steering in the Yaris feels like the power steering in my Xterra, and it seems the break hydraulics only repressurize when the engine is on. I cannot afford a Scangauge, but do I have to turn the car back to the on position without igniting the engine to have a more accurate mileage calculation? Plus, it gets a little cranky and likes to turn the engine back on if it has not spun down fully and it is a bit distracting to have to turn the car on and off several times to finally but the engine to sleep.
Is this true for the other hypermilers? It's funny, sometimes I feel like my car is off more than it is on!


Thank you
Alypuppy

09 HB Manual Trans.

Originally Posted by BailOut

I wholeheartedly disagree. The car only knows how to do its job one way, and that's the way the engineers thought it out. Their way is by far not the only way.

And cycling the ignition is not a "distraction". Your eyes don't leave the road, you still have assisted steering, and the brakes are good for 4-5 touches. Seriously, of all the things that one can gripe on for being a distraction while driving, cycling the ignition is at the bottom of my list.

There is a time and place for DFCO usage but it has two severe limitations:

1) It steals momentum.
2) The engine uses fuel again once any of its conditions are no longer met.

Coasting with the engine off is much more efficient in all aspects when you know you'll be coming to a stop for a while, or when you want to maintain more momentum in between the times you let the engine run.

Maybe not to you, but it is for the OP. If you're quoting me, it's because I was quoting the OP. I wouldn't know, I'd never be silly enough to kill my engine while driving.

[sbergman27]

Originally Posted by 1stToyota

I wouldn't know, I'd never be silly enough to kill my engine while driving.

It seems that some hypermilers don't care that much about safety, steering, or braking except insofar as particular techniques involving them might yield a half a percent increase in their MPG figures:

http://tinyurl.com/yg2e4kz

And honestly, to someone who's other car regularly gets in the 50-60 mpg range when driven normally... it seems a little silly to me to see Yaris drivers going to such lengths to go from forty-something to forty-something-point-one.

-Steve

[Bluevitz-rs]

Originally Posted by Yaris Hilton

No, you can't roll start an automatic.

That's not entirely true. The old 2 speed powerglide transmissions have a transmission pump on the output shaft making it possible to build enough pressure inside to spin the engine. Though I think you'd need to get it going about 20-30km/h before that would happen.

But as for the regular Auto tranny, not a chance in anything. In fact, you most you can't even flat tow because the bearings inside the transmission don't have any pressurized lubrication due to the fact that the pump is located on the input shaft. So without the engine turning you have no oil circulation and could end up with fried bearings.

PS, that goes for you hypermilers out there with autos. Shut your engine off at your own risk of doing costly internal damage while trying to save a few pennies of fuel.