Thanks for all your replies. I know that a diesel injector pump is lubricated by the fuel and you can burn them up if you run them without fuel. I wasn't sure if the same was true of a gasoline injector. That's why I asked the question. This isn't something I want to do with my truck, since it is my recreational vehicle and I only use it for towing and hauling loads.

The transmission operation is completely differentbetween my truck and the my car. The truck as well as my mini-van both have auto tranny's with over-drive. My Spirit has a three speed auto with direct drive lock-up when speeds are above 35 - 40 mph. I've noticed thevan and truck will unlock when I'm coasting, since I can see the tachometer drop when I'm coasting down a hill (still in drive). That is a feature that was installed to save fuel. The rpm's do notdrop as much on my car. I want to talk to my tranny mechanic and see what the differences are between the transmissions. But that is the reason I want to explore this idea for my car. If I can pick up a few more mpg with it since it is my daily driver that would be great. I am always observing and thinking about things and with the high cost of gas, I'm looking for ways to save money. I just don't want to do something that is unsafe or will damage my vehicle, so I'm asking questions first.

 

How high do the rpm stay in the car when coasting?

My ram's drop to below 1,000 when I coast. I also have an old lexus es300, 6 cyl, it drops to only about 1,400 when coasting, but for it that's low RPMs; normal driving load is above 2,500... in the pickup I hardly ever go above 2,000 rpm....

So, what I am saying is, maybe these thigs just don't compare as apples to apples...

 

the truck will shut the fuel off when costing on most all automatic vehicles! When coasting down grade the pcm will sence that there is minimal load then it will begin to thin the fuel off there's no need to shift into "N" as sometimes this can reduce your mpg due to the fact that I think (could be wrong) when in "N" the fuel system switches to open mode.. just coast and try putting about 7oz. of acetone in with every fill up you should see a 2mpg gain

 

When your throttle is closed, whether idling or on decel, you are using a very small amount of fuel. So little that you're not likely to have a measurable difference in economy if you shut it off completely.

The reason hybrid technology works is notbecause it killsthe engine on decel; it's charging the battery on decel and using the electric motor for acceleration, which is when a gasoline engine uses the most fuel. Hybrids cruise with the gasoline engine. Hybrids also don't do much better than their straight gasoline counterparts; usually only 10-20%. Most take years for the fuel savings to equal the increased cost of the vehicle. Then that all goes to pot when the batteries go belly up;Those NiMHand Lithium battery banks hit the wallet a little harder than a single lead-acid unit.