I use cruise a lot both because it's easier and because I have a STRONG tendency to be a leadfoot.

The problem here in hill country is that cruise is very wasteful. Downshift 2 or 3 gears and rev to the moon to maintain set speed going up hill, then downshift and engine brake (and rev to the moon) to maintain set speed going down hill. Not to mention it's annoying as hell. In particularly hilly areas I just hit cancel and reset when things flatten out.

Why couldn't they program an eco mode that allows, say, 5mph either side of set speed to eliminate some of the downshifting?

My wife’s RAV4 has eco mode. It does have a strong effect on how the car drives. It definitely changes shift points, and it dials down the AC considerably. Saturday we are headed to Costco. There are a lot of hills along the way. I’ll start out in regular mode and cruise and see how it does, then I’ll press the ECO button. I’ll report back my findings.

I run my '20 RAV in ECO mode all the time. HUGE impact on mileage, but haven't compared cruise use in other modes.

My 2018 Hyundai Sonata has several degrees of aggressiveness for maintaining speed in cruise control mode. Less “aggressive” is more “economy”.

I have an eco mode on my civic, (2015)
never noticed a diff is AC , I keep it set on about 65


I avg 35-36 mpg in the summer, maybe 34ish in the winter, using the onboard fuel mileage readout, not actual, (as in calculator when I fill up)

the cruise will do as you mention on hilly roads, but I usually apply my foot to keep the momentum up, esp since it is a CVT

quote:

Originally posted by Pipe Smoker:
My 2018 Hyundai Sonata has several degrees of aggressiveness for maintaining speed in cruise control mode. Less “aggressive” is more “economy”.

Interesting. How do you control the degree of "aggressiveness"?

Flat TX so no real hill info, but my Mercedes had a pretty mild CC, when set in Comfort or Eco.
It would apply the brakes (and brake lights) if it needed to slow going downhill, but wasn't aggressive about it.

Never tried CC in Sport or Sport+

Using cruise control to maintain speed and slowly accelerate is actually already more efficient than using the gas pedal for most cars. This is a trick used for "hyper-miling", which is a method of maximizing gas mileage in any car, even to the detriment of people stuck behind you. Plenty you can google, just don't be one of those fart knockers who now has a self-righteous reason not to go with the flow of traffic.

Even without being one of "those people," you can glean some extra efficiency by using cruise as much as you can WITHIN REASON.

We have a '21 Toyota Highlander Hybrid that has never been out of eco mode for the 20,000 we've driven it. Most of my driving is in cruise control since the adaptive cruise make driving so easy in or out of traffic. We have averaged about 33 MPG since birth. A good share of those miles are highway miles at 80+ MPH. It is well behaved on hill when going up and recharges the battery going down.

Who could ask for anything more from a 3 row SUV. I'd buy another in a heartbeat.

quote:

Originally posted by PHPaul:

quote:

Originally posted by Pipe Smoker:
My 2018 Hyundai Sonata has several degrees of aggressiveness for maintaining speed in cruise control mode. Less “aggressive” is more “economy”.

Interesting. How do you control the degree of "aggressiveness"?

you rub the shifter and say "wooooooossssaaaaah!"

quote:

Originally posted by PHPaul:

quote:

Originally posted by Pipe Smoker:
My 2018 Hyundai Sonata has several degrees of aggressiveness for maintaining speed in cruise control mode. Less “aggressive” is more “economy”.

Interesting. How do you control the degree of "aggressiveness"?

There’s a display I can see through the steering wheel. I can page through various control panels to get to the cruise control panel where I set the cruise control mode.

quote:

Originally posted by Pipe Smoker:

There’s a display I can see through the steering wheel. I can page through various control panels to get to the cruise control panel where I set the cruise control mode.

Ah. I wonder if the RAV has the same option? I may be reduced to (gasp!) reading the manual...

2022 Honda Ridgeline has eco-mode during cruise control. Averaged 26 MPG on a 100 mile drive this morning.

How much fuel can it really save?

I get trucks driving around hills, to save fuel. It doesn’t seem like it would take that much less energy to carry the same velocity, vs dropping it 10%.

Is it due to exchanging the existing kinetic energy to offset some of the negative acceleration of going up a plane?

Gravity is the same, mass stays the same, wind drag is a bit higher.

Increased mechanical losses due to increased RPM?

Drivetrain losses are the best argument for electrical drive trains, regardless of power source.

When I use cruise control in hilly country I still use the accelerator pedal to avoid what the OP is talking about. Going down big hills I get on the gas to take advantage of the hill and get a “run” at the he next uphill coming up. Using your gas pedal doesn’t not shut off cruise control like using the brake does.

On hilly roads, I take it off cruise as it's more efficient to build a little speed before the hill than it is to floor it once you are on the hill.

As for the revving while going down the hill, that's a benefit to you as it's not using gas, and it's saving your brakes from over heating.

What's interesting nowadays, is the newer 9 and 10 speed automatic transmissions don't offer enough engine braking to really slow the vehicle down, and the now have flashing warnings to let you know when you are exceeding the set speed.

I think any eco mode would control the speed the speed of acceleration when going up any inclines. That's what I notice when I have driven in cruise control. The car starts to go uphill, the speed goes down, the car adjusts to maintain speed as soon as possible.

When gas doubled in price, I decided to start driving using the eco-mode read out. It has a band that shows I'm driving economically and it goes out the band when I'm not. I notice that driving near the top of the eco band does increase my MPG while still accelerating although not as fast as I would accelerate otherwise.

I'm finding joy in this new pursuit and being safer. I do drive in the slow lane mostly now. When gas goes down to $2.25 again, then I'll consider going back to my old ways.

quote:

Originally posted by PHPaul:

The problem here in hill country is that cruise is very wasteful. Downshift 2 or 3 gears and rev to the moon to maintain set speed going up hill, then downshift and engine brake (and rev to the moon) to maintain set speed going down hill. Not to mention it's annoying as hell......

....Why couldn't they program an eco mode that allows, say, 5mph either side of set speed to eliminate some of the downshifting?

I seldom part company with you Paul but here I do. I drive on hills too, it's either up or down, a level section of road is rare and I wish my 2018 Ridgeline didn't behave on cruise the way you want your car to.

When set at say 75, when it struggles to maintain that speed with throttle alone going up a grade, it should downshift and back off the throttle a bit to maintain 75. (The rule of thumb how you know you're in too high of gear going up hill with a manual transmission is when you can't accelerate with throttle.) What the Ridgeline does is how you describe, speed drops to 74...... then to 73..... the car I just slowly passed is now gaining on me and moving over to the passing lane to get around me...... now at 72 with the car slowly overtaking me in the left lane, my truck downshifts, sometimes one gear then another as the grade is steepening, to prevent from dropping the apparent 4 mph tolerance, using full throttle to accelerate back up to 75. Now how does this behavior save gas?
Anyway after my previous vehicles which stayed within 1 mph (never more than 2) of set speed this is beyond irritating to me (as well as the other vehicles) and I wish Honda would correct it with a "mountain mode". BTW this is in regular mode not Econ, I never use that, it dulls the throttling down even worse making it run like a dog.
So why would Honda program this cruise to vary so much when my older Accord held speed? Having to accelerate 3-4 mph up hill to resume set speed is wasting momentum and energy so why? My hunch is in most scenarios allowing this large swing of speed is more efficient, it's programed to allow the large drop in the assumption the steepness of the grade will soon decrease or even level out which will permit the truck to work back up to set speed w/o having had to downshift. All well and good on rolling hills but not when driving up and down long hills and mountains. This kind of mapping might also be prioritized for the EPA MPG test cycle.

Gone are the days of 3 and even 2 speed transmissions which made for a very large increase in revs, torque, (and noise) when shifting down one gear. The whole reason for more transmissions gears now, typically 6 or more, is to get a tall top gear and close up the wide ratio gaps for almost seamless shifting so the motor can stay right in its power band, so they need to utilize it.

quote:

Originally posted by 1s1k:
When I use cruise control in hilly country I still use the accelerator pedal to avoid what the OP is talking about. Going down big hills I get on the gas to take advantage of the hill and get a “run” at the he next uphill coming up. Using your gas pedal doesn’t not shut off cruise control like using the brake does.

This defeats the purpose of what you are asking the from the vehicle.

I've been using cruise control to save on gas, but my commute is all flat road. I have not had good luck using cruise to save gas on hills, my engine isn't big enough to handle the hills efficiently when on cruise control. F150 w/4.6 modular.