"manual" cruise control

[lusth]

Hi all,

Just came home from the dealer with a new Pontiac G5 XFE, 37 mpg highway. It's rather hilly in northern Alabama, so I tried something that looked like it would give me a significant mpg boost compared to straight cruise control. I'm wondering if it makes sense.

From reading the forums, cc is not optimal since it will accelerate a car up a hill. So what I did was tap the "adjust down" cruise control button periodically as I went up a hill and then tapped the "adjust up" button going down. After a while, this became natural and I didn't even think about it (the buttons are nicely placed on the steering wheel). The instantaneous MPG reading on the info panel (great feature) seemed to show improvement.

This wouldn't work on my wife's Honda CRV because when you tap down, the car overshoots on the slowing and then accelerates back up to get to the new speed. On the G5 however, the adjusts are smooth as silk.

Oh, and I also cycled the AC - off up the hill and on down the hill. It's hot, hot, hot, in the summertime!

Sorry if this has been discussed but I could not find anything like this in the archives. Just high tech mods of cc for constant mpg.

In any case, is this a smart strategy?

thanks,

john

[elhigh]

In my experience, it is a smart strategy. Like your wife's car, the cruise on my Forester will overshoot on the decel, so I don't do that much - but clicking off the AC on some of the uphills has the notable effect of avoiding the torque converter unlocking, and sometimes even evading the tranny downshifting. The first-gen Forester's auto will unlock and downshift if you glare at it angrily, which drives me crazy - there's torque enough that that's just silly.

The downside is carpooling with Sweetie. When I'm doing all this, interacting with the car and its environment so as to maximize its fuel economy, Sweetie's lips get thinner and thinner, until finally: "Will - you - STOP - fiddling - with - all - the - danged - BUTTONS!"

And frankly, I have had to back off of that. I've got a couple of kids starting to drive, so I want them to pay much more attention on keeping lanes and not merging into other cars, and let them pick up ecodriving when their proficiency improves.

[cfg83]

lusth -

Welcome to EM! I've done similar tap up/down on my wife's Civic, but I never posted that strategy.

When I am driving her car with CC, I am modulating it all the time. But it's not second nature, it's a very conscious "road context" thing for me.

It's cool that you get instant MPG. I wish that instant/AVG MPG had become part of all car ECU/PCMs with the 1996 OBDII implementation.

CarloSW2

[whokilledthejams]

Hell, I get yelled at for obeying speed limits.

Still, lusth, you're doing everything right. Little things like that go a long way towards helping your FE without a huge effort.

I have an aftermarket CC on my xB, and the gain is set pretty low by default, so I actually lose speed up a good hill. Where I normally drive, it gets the job done.