Comments on: Does Cruise Control Make Cars More Fuel Efficient?

By: DavidK

DavidK — Thu, 11 Dec 2008 14:40:55 +0000

I’ll completely agree with marci. I have to do the same thing when I drive long distances. I get aggravated sometimes and just have to pass people.

One other thing about fuel usage minimization while using cruise control is exactly what I stated above. You’ll notice yourself passing people less and doing the “accelerator shuffle” (i.e.- on and off the gas a lot) a lot less. This helps to maintain a steady flow of fuel. And at highway speeds, the engine is barely working so having a low and steady fuel flow means that you average out to using less of the stuff.

By: marci

marci — Thu, 11 Dec 2008 05:24:59 +0000

I don’t know about the gas mileage.

I just use the cruise control to keep my leadfoot
from getting a speeding ticket

By: Brian Lang

Brian Lang — Wed, 10 Dec 2008 22:22:10 +0000

I use a similar technique to obsolete29. Most of my route to work is flat, but the last stretch has a sizable hill. I usually cruise at 70 km/h on the flats and let it fall off to as low as 50 km/h going uphill (don’t want to make other drivers too angry…). Then when I get to the top, I’ve found that if I set my speed at 80km/h for a short stretch, I can coast the entire remaining distance to my parking spot.
I’ve found that the trick to better mileage on my car (2003 Chevrolet Malibu) is to keep the RPMs between 1000 and 2000 – Lower is better. The higher the RPMs, the more fuel your car needs to burn to get them up there.
The other important ingredient in better fuel economy is keeping your tires properly inflated or even a tiny bit over inflated (no more than 5psi over). Check it weekly.
I’ve found that using these techniques has stretched my fill ups from once every 4 work days to once every 6 or 7 work days (depending on what errands I run on the way home). My round trip commute is a little over 66km.

By: Clair Schwan of Frugal Living Freedom

Clair Schwan of Frugal Living Freedom — Wed, 10 Dec 2008 21:11:49 +0000

The approach used by obsolete29 is valid, although a bit different than mine.

The main point is that you have to gently accelerate a bit to gain sufficient speed to keep your car in top gear while climbing a hill. The higher the hill, the greater speed that’s needed. On the other side of the hill you make up for the fuel used to climb it.

If you let cruise control take you up the hill, it will drop you down into lower gearing and rev up the engine in an effort to maintain the same speed (because that’s what you asked of it). It has no way of knowing that you are approaching a hill until you’re on it.

The advice from Edmunds is correct – cruise on the flat and gentle grades, and use manual control on the hills.

Here is my approach: use cruise until approaching a hill, then gently apply a bit more gas to gain speed for momentum to climb in top gear, letting off of the gas as I near the crest, then letting cruise control once again take over near the top. This approach keeps me in top gear and best fuel economy.

Your advice about a speeding ticket is good. Keep your speed reasonable and don’t build it up too far in advance of the hill.

Clair

By: obsolete29

obsolete29 — Wed, 10 Dec 2008 20:42:56 +0000

I have to commute to work about 3 times a week (87 miles one way) and I use my cruise on the mostly flat stages and manually navigate the hills… disengaging the cruise and traveling slower up the hills and coasting down the other side. Once I’m back to normal terrain, re-engage the cruise; best of both worlds.

By: Scordo.com

Scordo.com — Wed, 10 Dec 2008 20:08:45 +0000

@Andrew. Cruise control may actually manage engine performance (fuel push through, torque, etc.) a little more efficiently than breaking and accelerating manually. It’s the same principle behind ESC (stability control) which applies braking and engine management when the computer notices wheel spin or excessive breaking; a “normal” driver cannot perform the same task with the same safety and efficiency.

By: Frugal Dad

Frugal Dad — Wed, 10 Dec 2008 20:04:45 +0000

@Andrew: Thanks. As I indicated, my “eye-balling” the fuel gauge was less than scientific–much less! Sounds like you have done more extensive testing. I’m leaning towards the belief that cruise control should only be used on level stretches of highway with no traffic. Even then, I’m not sure it is much of a gas-saver.

By: Andrew

Andrew — Wed, 10 Dec 2008 19:48:38 +0000

There’s nothing magical about cruise control, you use the same amount of gas to maintain the same speed with your foot on the pedal. I did a 2 year long experiment and tracked my mileage religiously. The biggest impact on mileage comes from stop and go driving. I got a job close to home (2.5 miles) and saw my mileage in my 2005 Tacoma drop from 25 to 16.5 MPG.

To get a more accurate result you’d have to fill up before a trip and fill up again right after to figure out how many gallons were consumed. You’d then have to repeat the same trip with cruise control on so you are comparing apples to apples.

By: Andy @ Retire at 40

Andy @ Retire at 40 — Wed, 10 Dec 2008 19:12:38 +0000

Well, I’m not sure about cruise-control but I know by selling my car last week and choosing to cycle everywhere, that I am much more efficient both in terms of cost and gas used!

But seriously, there are so many other costs of keeping your car over and above gas, it’s almost sad now I think about how much I used to waste just owning a car, let alone driving it.

By: Scordo.com

Scordo.com — Wed, 10 Dec 2008 19:05:36 +0000

Most of the newer vehicles on the road today do have sophisticated engine management programs helping the driver (including cruise control, electronic stability control is another example).

Edmunds is pretty much correct in stating that in most conditions crusie control can help with fuel efficiency (hills will kill your MPGs gained via using cruise control).

Some higher end vehicles actually offer a radar based cruise control system, which is pretty cool.

http://www.scordo.com/blog/blog