Improve mpg when using cruise control?

Other than deciding when to cancel it and re-engage it, no.

But you'll spot opportunities where timely cancellation & engagement make for smoother control and fuel savings.

 

Does your particular kit have any user adjustments to control the rate of catching up to speed? This is where you'd take care of that hard acceleration and deceleration/regeneration.

Factory cruise controls generally get better MPG than average drivers in average conditions, but not as good as the more MPG-aware drivers.

 

The DRCC on my Prime will follow the car in front of me to a dead stop and then resume by itself if the stop is less than about one second. If it's longer, it takes a bump of the "resume" lever or a nudge on the gas pedal and it will continue following. I haven't heard of that feature on the c, but I'm not very well versed on that model.

 

In the old days, it would have been an adjustment screw on the side of the control box. Today, it could be much different. But without an installation manual, in the kit or online, there probably isn't much you can do.

 

As far as improving mpg..

When I drive with cruise on, I will tap down a few mph when climbing a hill
and then after cresting it, I will tap back up a few to resume the same mph.

Many factors depend on how much or if any with the size of hill, traffic, etc.

I do not use cruise all that often, just on longer highway trips.
I think I can do better mpg w/o however on longer trips it seems necessary for less leg/foot fatigue.

 

I find the OEM cruise does pretty good for mpg, use it a lot. You will of course be able to do better when looking ahead, coasting up to slow downs, that sort of thing.

 

I have found (…over the last 83k miles I've driven in my 2009 Gen II) the best trick is to NOT try and second-guess those crafty Japanese designers of the amazing Prius! (…but, as always YMMV)

 

I generally do likewise when traveling to places with hills. Sometimes I just turn it off. But I do like to use it as much as possible because it allows me to keep more of my focus on the boneheads on the other side of the glass. And it's just less tiring.

 

I'm not sure I'd call it an undocumented trick. It's a modern cruise control so it has downshift authority, you can use it for speed control going down a mountain unlike the classic throttle-authority cruisers.

The cruiser will resume a previously set speed if the current speed is above 25mph.

 

I'll just remind folks that some of us still have modern cars that don't have this downshift authority. Just for yucks, I tested my '14 Forester on a usual long steep hill last week. Top gear held speed on the upper half the hill, then started running away on the lower half. I downshifted one gear, same result. So I downshifted a second notch, then speed held even without CC.

I haven't yet seen any modern cruise control that can operate that style of clutch by itself.

 

Maybe that's one reason I'm reluctant to use cruise on a downhill. It just seems a little nuts.

I look to cruise as a way to keep up speed; rolling a ton or two of steel down a steep hill, I'd rather be in charge. The dynamics change. On level ground weight and drag is a big factor, tempering everything. Rolling downhill, it's much more just mass and inertia, you're in partial free-fall.

 

This is a $20 aftermarket kit?
You're lucky it works period. Surprised anything like that is even legally available.

But basically, by definition "Cruise Control" is an AUTOMATIC operation. You're choosing to allow the vehicle to maintain speed. So tricks to make basic cruise control more MPG efficient aren't going to exist.

Depending on your dedication and skill as a driver, you may be able to drive duplicate routes without cruise control and get better MPG, or worse, but basic cruise control is just that...it's going to set a speed and maintain and that is simply going to use the fuel it is going to use.
Especially if we are talking about a system installed aftermarket.

The newer radar assisted systems may be different.

 

Cruise control doesn't hinder use of brakes or downshifting. No harm in using it while it works and then going manual if and when needed. I just use it if it helps and don't use it if it won't help. Either way, I'm in charge.

 

I want to be in charge and have no one else on the bridge, on a steep down hill, LOL.

 

If it's THAT steep, cruise wouldn't be much good anyway, right?

 

Yeah especially with your co-participants, who can't wait to get by you, get back to doing 80K (kmh) in a 50 zone.

There's one hill around here, city planners in their wisdom plunked a middle and high school right at the peak of it, and it's roughly 2.5 kms up then back down. About 50% of is best done in B, including the last bit, which culminates in a traffic light, usually red. If you don't use B (and even with), you end up with a full-to-the-gills battery (well maybe not you with a Prime).

City planners seem to think in 2D, way too much. We were walking the dog around a new up-the-hill development this morning, as usual everybody's driveways are super steep, with sharp dips/crests. Walking one hairpin corner, my wife pointed out how she kicked a fir cone and it kept rolling, lol.

I think we landed on our feet, buying in the flat lands at the bottom, "Lower Eagle Ridge" I like to call it.

 

The best trick is to learn all the ways to get high MPG without using CC. Basically, it's taking advantage of momentum. Anticipate certain strops by slowing down sooner and coasting to them. Start out from stops slower. When on the highway or any open road that allows higher speeds, slow down a few mph when going up a hill, and take advantage of the down hills by coasting to the highest speed your are comfortable with. CC doesn't allow you to do these things without a lot of constant fiddling.

If your trip is on mainly flat roads you can save some gas with CC. If you are on a long trip, want to stay comfortable and not get stiff, then use CC. But I have found that in most cases, once you learn the driving techniques that eventually become second nature, you can probably beat the CC when it comes to gas mileage.