In a continuing effort to save gas, I have a question. I noticed coasting down hills, the RPMs stay between 1500-2000. To save gas, I can switch the trany into neutral and have the RPMs below 1000. Is this a good idea? Will this cause wear on the trany?

 

It is ok for your transmission to coast down a hill. However, it is actually illegal to coast down hills in many (if not all) states.

 

I forgot to add, I have an auto trany.

 

no it shouldn't hurt it at all. It will increase your milage too if you have a long downhill straight-away. Won't notice too much of an increase on short hills. If coming from denver, I usually throw it in neutral once I get through the Eisenhauer tunnel and coast the next 10 miles descending over 2000 feet. Done this in all the vehciles I've owned up here and never a problem. This is actually really common in other countries too as their gas prices are extreme compared to ours

 

put it in neutral when stopped in traffic or extended stop signs this can be up to a 5 to 10% increase in idel effeciency.

 

Before we advise to put it in neutral to coast down hills, we need to determine if the fuel shuts off when the wheels are turning the engine, as happens when going down hill.
Some vehicles shut off the fuel, which would use less fuel than maintaining idle in neutral. Plus the fact that in neutral you would use more brakes to keep from gaining speed, which would probably offset any perceived fuel savings.

 

The RPM of the engine may be higher but, as said above, it may just be the tires spinning the engine faster ( engine braking ).

I know the onboard MPG computer isn't that accurate but is there a different when in nuetral going down a hill then when in gear?

 

If you are at the point of saving gas by putting the car in neutral...perhaps using a Jeep as your daily driver is not the best financial choice for you

Just saying....

 

When people ask me what mileage I get I tell them " I don't know, I didn't buy it for fuel efficiency, my Toyota 4runner got 25 MPG with 33s and the A/C running "

 

My sentiments exactly. I tell people my other vehicle gets 55 mpg highway and 48 mpg around town (VW TDI).