You can use P&G, just leave the engine running for the neutral glide part. Does it say something like "under 35mph and less than 50 miles"? If so, you can turn the engine off at "under 35". They were willing to put it in writing and risk lawsuits, so there's probably a safety cushion built in there as well. I'm not recommending that you exceed the specs, but you probably can. ;)

It doesn't specify. Doesn't sound like I should do it at all.


So what CAN I do? Other than the typical maintenance stuff (tires, air filters, etc) and driving the speed limit. Doesn't sound like hypermiling with an automatic can yield very significant results.

I'll let you all know if my gas mileage is any different after I check it the next time I fill up. This is my first tank of gas using these techniques so I'm interested to see if there's an improvement.

If the engine is running, you can glide in neutral ALL DAY LONG. That will definitely help your mileage. My civic idles at .3gph, so it you're coasting at 30mph, that makes 100mpg. Mixing any amount of that into your drive will help the average.

Also, try driving as if you have no brakes. Use extreme forward-looking anticipation.

My cars transmission (automatic) downshifts as your speed drops instead of just dropping to idle.

YMMV as they say... Neutral coast vs in-gear coast efficiency will depend on the deceleration fuel cutoff logic that your GM ECU uses and the RPM range, gearing and TC lockup points. Motors generally have relatively little frictional loss below 3000RPM, but this goes up to 20% of the motor's output at 5-6000 RPM, so it's possible that if you've got overdrive gearing and it's loafing along at 2000 RPM with the TC locked at 60mph, and the DFCO acts down to 1000RPM, and the TC stays locked up when you take your foot off, down to some reasonable speed like 30 or 40mph.. then what you may find by experiment is that P+G between 60 and 40 is more efficient in gear than neutral coasting. If however, the TC unlocks and the revs drop quickly below 1000 when you take your foot off, or it downshifts early, or you have high gearing, so you're slowing in the 3500-2500 range or higher (Engine friction higher), then you may find that coasting in neutral is more effective.

GM ECUs are meant to have a semi mythical lean burn mode at steady state cruise, so you might try driving 60mph steady, and seeing if that seems to make a difference. We often hear of folks with buick V6 powered vehicles, the 3800 or later versions thereof, getting low to mid 30s highway.

Hypermilling etc..
 

It is nice to see someone else with a Cutlass Supreme on here. Have a 91 myself.

Tried neutral a couple of times, not sure how much it helped though with mpg.

The car itself is pretty good for gas mileage. Here are a few things that I have done to increase my own.

-Using 5w30 instead of 10w30.
-Using cruise control
-Installing an air dam on the front (still in testing this week)
-Limiting/eliminating use of a/c

Hope this helps
Joel

so should I try and see if P&G helps any without shutting the car off, but just going in neutral?


and thanks Joel for the info

You are very welcome.

Joel

Yes, Most of my P&G is with the engine on and it does work; though the pulse part seems like it's using lots of gas, the glide more than compensates for it.
Cruise control saving gas is debatable. Most people can out preform the cruise if they are paying attention.It may help if you're tired and don't feel like hypermiling.

Personally cruise control has worked. Last few days been acting up, need to get it checked.

Early on that is what made a difference.

Joel