The other day one of our senior members who has proven himself to be one of the best hypermilers in the world stated that an effort should be made to back into a garage to somehow save gas. I've been thinking about this for a couple of days and I can not see for the life of me how backing in to a garage saves any gas. In fact I'm quite certain that in my case backing in would increase fuel consumption slightly.

Currently I cut my car off a mile from home and coast into my garage nose first, ICE off. This takes zero gas. Leaving the garage is easy as I live on a lightly traveled road. To back out I put in in R, start the car and back a short distance in my driveway. Once the car is in the road I put it in a forward gear and start driving.

If I were to back in I'd need to restart the car before putting it away. Backing in is also slightly harder so I'd use a tiny bit more gas puting the car away. Pulling out would be faster because the car would alread be facing the proper direction.

Because backing into a garage is more difficult than backing out of a garage I'd say slightly more gas would be used backing into a garage.

 

I say it depends almost completely on your situation. I drive my car into my 'spot' (some bricks on the front lawn) forward for similar reasons as you, I can just coast in without fuss, and for leaving all I do is back out into the driveway and head out forward. The Prius lives in the carport, and it works best to back it in so that the driver door is on the same side as the house, plus it makes leaving in the morning much quicker (that's usually when it matters more) and reverse in the Prius is EV mode, so no problems with backing in as far as saving gas goes.

 

On a fairly level roadway/driveway I'd have to agree with your friend, simply for the difference between a hot and cold engine.

When you arrive home your engine is completely warmed up, even to the bolts that hold the engine.

All ICE's are fuel pigs when cold (Compared to when hot)

Given that fact, it should take little gas to swing around & back in with a hot engine...compared to starting a stone-cold motor and having to back out, swing it around before getting down the road.

Of course we're talking about only a small amount of fuel here but as we know little savings can add up.

Schwa has a point in that the EV mode of Prius should defeat that rule.

 

I understand that a hot engine is more efficient than a cold one. One way or another you must enter your garage with the engine hot and leave your garage with the engine cool. It makes no difference if you are going forward or backwards. If the car is pointed nose out the car is still cold as it goes down the driveway and is still burning more gas than it would if it was warm. The only possible time to save gas by backing into the garage is the small amount of time it takes to shift from reverse to a forward gear. This is more than offset in my case by the gas burned getting the car turned around in the first place.

I suppose if you lived on a busy road it would be much better to have you nose to the road, so you can enter traffic easier. Were I to live on such a street I'd back in just to be able to get out easier, not to save gas.

 

To start a car from a stop takes energy. It takes more energy in a cold car than a warmed up one. I also agree that for the most part a prius or any car that can stay in EV mode during the turn around probably won't gain much if anything from this since the b attery energy will probably come back on your first down hill or whatever.

However, in a IMA based hybrid where it uses the engine for moving the car from a stop it more than likely will save some gas. Obviously its up to the individual to determine if the gas saved is worth the hastle. This is one of the cases where there is a slight gain that by itself probably won't gain you anything, but people that are looking for every drop may want to consider it.

 

unfortnately i'm one of those unlucky owners with a hill driveway that swings left into the garage. And I have to use any momentum from the road to climb that hill so that I can enter the garage without gassing and without stalling. As well backing in with a manual uphill stinks since you have to burn a lot of clutch to prevent sliding down again. I understand when your on a hill, the car rolls back a bit, is this too with the prius?

 

You have just put into words what I thought when I read the same Post. The other thing that has not been mentioned (I-Don't-Think) is that after going through all the moves it would take for me to back-in you still have to be able to get out of the (Vehicle). Major-Problem (SPACE) Can't Get Out !!!

Not For Everyone; HUH???

Terry

 

On a steep hill it's possible to roll back if you just take your foot off the brake. The Prius II introduced more aggressive holding, but I'm pretty sure it will roll back given a steep enough hill, but I haven't checked this out. On the flat it simulates an automatic transmission's creep when you take you foot off the brake, but it doesn't have to, they just did it so people get what they are used to. Pushing an AC motor forward while it's moving backwards isn't a big deal, there's no added friction.

 

I know it probably wasn't me that said it but I did say it a few weeks ago here on one thread or another. Anyway, I am able to glide down the last 100 feet of my road then swing in at an angle to the right. Then I pop the car into reverse and another 40 feet into the garage. I don't have to do the creeping manuvering most people have to do so the whole process is maybe 7-10 seconds.

If I were to back out of my garage I have to do a bit more manuvering but it IMO a warm engine is more efficient than a cold engine. So if I have to spend that extra 7-10 seconds (maybe a tad more back out of the garage) I "might" be saving some gas. On the other hand, that extra 7-10 seconds (maybe more) just might be what I need to get me (my car warm enough) to go into autostop while I wait 3-7 minutes to find a place to accelerate like a madman in traffic when a tiny opening shows itself. (0-70mph)

Actually my MASTER PLAN in the next year is building a new garage with doors on both sides! Pull in; Pull out. (before anyone comes up with the "That's stupid, why would you do that?". I spend mucho time in the garage and it'll create a nice and breezy open garage for when I'm working in there.

 

The point of backing into the garage is that you do more driving when the engine is hot and less "non productive hypermiling" in the morning when it's cold. In other words, the act of leaving in the morning with the engine cold now becomes faster, since you just start up and go forward; there are not multiple manouvers.

A perfectly valid point I think.