Right foot versus cruise control

[7eregrine]

A few people here presume to think they can get better gas mileage by using the accelerator themselves. Personally, I disagree. The computer, keeping your car at a perfect constant or near constant speed will beat a human every time.
So I got on the freeway today and reset the mpg. Turned on cruise. 30 minutes later I got off the freeway.
Challenge: come beat this, humans. [emoji16]

 

[Xeler8ing]

Be careful what you wish for!

Some European diesel owners might get better mileage without cruise control!

 

[sjtilney]

Given that it's 37 degrees outside, I would expect a little better gas mileage with the dense air. Usually on very cold days, I can get close to 38 MPG on a flat highway, going 65 MPH. Are you at a high altitude?

 

[ColoradoDriver]

Hehe, may have to try that.

Truthfully though I don't really use my cruise control. I have little opportunity to, and when I do, I usually forget it's even there.

 

[yugrus]

Try that on hilly terrain...

 

[craigo]

Given that it's 37 degrees outside, I would expect a little better gas mileage with the dense air. Usually on very cold days, I can get close to 38 MPG on a flat highway, going 65 MPH. Are you at a high altitude?

The denser air is usually offset by the lower volatility of fuel. The engine taking longer to heat up will also affect it, especially during short trips. Sweet spot for most engines is ~70 degrees.

 

[7eregrine]

Given that it's 37 degrees outside, I would expect a little better gas mileage with the dense air. Usually on very cold days, I can get close to 38 MPG on a flat highway, going 65 MPH. Are you at a high altitude?

Around 600 feet above sea level. So, no.

 

[7eregrine]

Oh and my point still stands, regardless of the circumstances. A diesel on cruise will beat a human driving a diesel. A car driving through hill country on cruise will beat a human.

 

[bmninada]

I have adaptive cruise control. Time and again - it beats my right foot.

 

[Xeler8ing]

Oh and my point still stands, regardless of the circumstances. A diesel on cruise will beat a human driving a diesel. A car driving through hill country on cruise will beat a human.

A diesel on cruise driven by a human will beat a petrol(gasoline) driven by a computer.

 

[Red MC]

A few people here presume to think they can get better gas mileage by using the accelerator themselves. Personally, I disagree. The computer, keeping your car at a perfect constant or near constant speed will beat a human every time.
So I got on the freeway today and reset the mpg. Turned on cruise. 30 minutes later I got off the freeway.
Challenge: come beat this, humans. [emoji16]

You didn't post your route, your average speed, weather, traffic conditions, tire pressure.
You also didn't post a result without cruise control on the same route under the same conditions.

Seems like a troll.

But I'm curious to know why you think cruise control will beat a human. If you think cruise control will hold a constant speed with less variation than a human, then I generally agree. If you're on perfectly flat terrain with no traffic and no variation in wind, then holding a constant speed should be better than varying speed with the same average. Because drag is proportional to the square of velocity, the extra fuel burned above the target speed hurts you more than the fuel saved below the target speed. But as soon as you throw hills and traffic into it, the answer is not so obvious anymore. In my anecdotal experience, driving on hilly terrain without cruise control, I seem to get better mileage by taking more of a constant throttle approach: gradually dropping below my target speed up hills and making it up on the downhills. Especially with turbo engines, using a lot of throttle to maintain a constant speed up steep hills seems to suck fuel quickly.

 

[Chris_Top_Her]

I don't think any trolling is happening here..(group)

 

[7eregrine]

Trolling lol Come on Red...
14 months I've had this car. I never hit low 30s for a length of time on that gauge. It his 34.4 at one point. Insane!
Doesn't matter the condition, the computer will beat you every time. The computer will always keep a steadier pace in the flat then you, will always give it the right amount of gas going uphill or let off at the perfect time going down.
I'm only suggesting if you really care about mpg, then you should use cruise more.
My opinion, of course, after decades of driving. Could there be some amazing driver out there that is the exception? No question.
But for most people, cruise wins.

 

[yugrus]

I dunno. On our '15 the cruise goes right into fuel shut-up mode as soon as it senses the downhill. And it keeps it this way right until the uphill, at which point it gives it a WOT. I'm sure I beat it all day long with my right foot in this case. I bet the foot is 50+ years old, and some computers are better at hills then it is, but I still beat mine.
Flat terrain? Yeah, I wouldn't even bother competing...

 

[Buzzman12]

As soon as you throw hills and traffic into it, the answer is not so obvious anymore. In my anecdotal experience, driving on hilly terrain without cruise control, I seem to get better mileage by taking more of a constant throttle approach: gradually dropping below my target speed up hills and making it up on the downhills.

On a flat terrain, I can see why cruise control is better than a human foot regarding maintaining speed and getting better mpg's,
But I agree with Red here that when you throw in the hills, up and/or down, the equation changes.
In almost all of the cars I've owned that had cruise, when going up an incline, (especially if the car was loaded with people and luggage), the engine would rev up, and the tranny would drop down a gear to try and maintain speed.
Trying to maintain 75mph on a long uphill stretch of highway would suck gas like crazy.
I always disengaged the cruise in these situations to save the car from going into passing gear.
Slowing down a bit in these situations never bothered me, and it saved the car from having to over exert itself.
Going down the other side, the car would speed up (no auto brakes on the older cruise systems) and go faster than the set speed.
All in all, I use my cruise whenever I can, but I take over manual control in hilly terrains.

 

[Puyapim]

I agree with the premise that cruise engaged on flat roads will outperform the human foot but hills in my experience do better with the foot. As Red MC mentioned, by going a bit slower up the hills you will do better on the economy.

 

[7eregrine]

I think someone just needs to do it that lives somewhere hilly. [emoji4]
Come on car needs.

 

[shadonoz]

I agree with the premise that cruise engaged on flat roads will outperform the human foot but hills in my experience do better with the foot. As Red MC mentioned, by going a bit slower up the hills you will do better on the economy.

Of course, the slower you can go in top gear, the better the economy-- on the flat or uphill !

 

[7eregrine]

I bet the foot is 50+ years old

Oh...and you'd lose that bet if you're referring to my foot. [emoji16]

 

[Puyapim]

Of course, the slower you can go in top gear, the better the economy-- on the flat or uphill !

Definitely. For example I saw just over 33mpg on I-5 at 60 mph but as soon as I hit the 70 mph speed limit section it dropped to around 28+. My experience so far is that the 45-60 mph range is the sweet range for best fuel economy. Generally speaking, that’s true for most vehicles. The CX5 is very throttle sensitive though.