Cruise MPG vs Foot MPG

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Cruise MPG vs Foot MPG

January 08, 2011, 11:25:22 am

I have been told by various RVers that they do not use their cruise control unless on flat land because it keeps shifting the tranny. Also they felt they got better MPG when they controlled the speed instead of the cruise control. True? Not true? Has anyone tested this and been able to discern any difference.

In reality cruise control is a luxury item we all enjoy having, but is it the best way to economize with fuel prices going thru the roof?

Re: Cruise MPG vs Foot MPG

Reply #1 – January 08, 2011, 11:34:50 am

Quote from: nitehawk – January 08, 2011, 11:25:22 am

I have been told by various RVers that they do not use their cruise control unless on flat land because it keeps shifting the tranny. Also they felt they got better MPG when they controlled the speed instead of the cruise control. True? Not true? Has anyone tested this and been able to discern any difference.

In reality cruise control is a luxury item we all enjoy having, but is it the best way to economize with fuel prices going thru the roof?

Cruise control is a function all vehicles have, but most people with vehicles don't use. With gas prices on the rise, consumers are looking for any way to save money on gas. Using cruise control is an effective, and safe way to save money on gas. Most drivers feel the need to drive aggressively. They drive at higher speeds, and brake unnecessarily. Using cruise control may seem like an odd change, but it can make a major difference in fuel efficiency. Some may find it hard to believe, but cruise control does make the cut when saving on gas.

Maintaining a steady speed will improve your vehicle's gas mileage. Cruise control makes the driver take a long view of the road instead of reacting to every change around them. Also, cruise control smoothes out the driver's accelerator input by preventing nervous surging. You will be safer, more relaxed, and you'll increase fuel efficiency when using cruise control.

Using cruise control cuts down on unnecessary speed changes, which can eat up gas, and it prevents the driver's average speed from increasing with time on the road. Traveling the speed limit, and using cruise control whenever you can will increase fuel economy. Using cruise control is best for open city driving, and highway driving. When tested on a highway a Land Rover LR3 got almost 14 percent better mileage using cruise control set at 70 mph rather than cruising at driver controlled speeds between 65mph and 75mph.

Cruise control is great for open city driving, but it's not practical in stop and go traffic. For stop and go traffic, it is best to drive the speed limit. Driving at the speed limit will give you more green lights. Which not only increases gas mileage, but it also reduces wear on your brakes. The DOE says that every 5mph you drive over 65mph represents a 7 percent decrease in fuel economy. If you are driving 75 mph on the highway, slow down to 65 mph. It will make a major difference. Wind resistance increases with speed every mile that you drive over 55mph and your fuel economy goes down by two percent. You'll get about half the mileage driving at 70mph compared to 50mph.

It would also be smart for drivers to anticipate stops in stop and go traffic. If you're at a stoplight don't speed away, there's a good chance you'll have to stop again soon. It's best to accelerate slowly, and then coast to the next light. If you see a need to stop ahead, then coast. Don't continue to accelerate then brake at the last minute. If you anticipate stops, you'll cut down on your wasteful acceleration, and save fuels.

It is also practical to drive in the highest gear possible. Driving in the highest gear saves up to 14 percent, but the average savings are 7 percent. Driving in the highest gear works, because the slower the engine turns, the fewer the number of explosions in the cylinders. Fewer explosions means less gas consumed. Besides using cruise control, driving in the highest gear will save you an additional $0.21. This number may seem small, but the savings are significant when paying $2.90 for a gallon of gas.

Using cruise control is practical, but it's only practical when driving on flat terrain. Some drivers have gotten the idea that it is best to speed up when driving uphill. It's not a great idea to speed up when traveling uphill, because the cruise control function will try to keep you up to the speed you've set and will use a lot of extra gas down shifting to lower gears to accomplish this. If you're driving on hilly terrain, using cruise control typically causes your vehicle to speed up faster (to maintain the preset speed) than it would if you were operating the accelerator yourself. Even though using cruise control is not practical for driving uphill. There's still no need for aggressive driving.

Using cruise control, over conventional driving methods is an obvious choice. Many drivers have the habit of driving above speed limits. Going fast can be costly. Not only is there a risk of speeding tickets, driving at higher speeds is a waste of gas. People drive aggressively when they're in a rush. Many don't realize that using cruise control and driving the speed limits will get you to your destination in a timely matter. Mashing the accelerator pedal from a stoplight, braking hard, and speeding all contribute to decrease in fuel economy. It would be in all drivers best interests to hit the cruise control sit back, and relax. It may seem like a major change from your normal driving routine, but it's a much-needed change. Drivers will not feel so uncomfortable using cruise control, once they see the difference in their pockets.

When not to use cruise control:

Cruise control can be dangerous where you cannot drive safely at a steady speed.
Also, do not use your cruise control on winding roads or in heavy traffic. Cruise control may also be dangerous on slippery roads.
On such roads, fast changes in tire traction can cause excessive wheel slip, and you could lose control.

Re: Cruise MPG vs Foot MPG

Reply #2 – January 08, 2011, 01:36:28 pm

This is one of those "there AIN'T no one answer, questions.

Can a really skillful driver do better than a cruise control-- yes.

Can the average driver do better than a cruise control-- no.

Places a skillful driver can "out-think a cruise control:

Rolling hills, where a PROactive driver sees the crest is near and backs off, knowing that the lost speed will be regained on the downslope.

Freeway overpasses-- while a cruise will add throttle, a skillful driver will do NOTHING-- again, knowing that within a few hundred yards, speed will be back where it was.

And all cruise controls are not the same.

Options: Soft cruise vs hard cruise (allows more MPH change before adding more fuel).
Drive in economy mode (Allison) so those full throttle applications (either by driver or cruise) will not go from, say 6th gear full throttle to 5th gear full throttle since 5th gear full throttle will raise the RPM's AND fuel consumption.
Disable engine brake/retarder in rolling hills, or set so it only comes on after XX miles above set cruise speed.

Brett

Re: Cruise MPG vs Foot MPG

Reply #3 – January 08, 2011, 02:08:54 pm

Full agreement with Brett, even on my 2011 Ford F350 with the new Ford Diesel 6.7L engine, when going down hill it down shifts to hold back, then as it starts p the next hill it down shifts, goes to WOT, and the computer shows mileage down to 2.6mpg for a wild acceleration to the set speed on the cruise control. Driving by foot, the driver can control all the above with ease.
Do what feels good. If you like the cruise, do it, for me, I use it a lot on flat land running, when get to hills, rolling hills or mountans, I am on the foot.
Cheers

Re: Cruise MPG vs Foot MPG

Reply #4 – January 08, 2011, 03:23:15 pm

don't bother with this:

Disable engine brake/retarder in rolling hills, or set so it only comes on after XX miles above set cruise speed.

I learned really soon to keep the retarder joystick fully forward when using cruise control. Otherwise, the first downgrade will have the cruise back-off the throttle, applying the retarder, disengaging the the cruise control. Oops.

Re: Cruise MPG vs Foot MPG

Reply #5 – January 08, 2011, 03:26:13 pm

I also do the cruise control only on flat terrain...off in hilly areas.

Re: Cruise MPG vs Foot MPG

Reply #6 – January 08, 2011, 03:36:03 pm

I use cruise on the flat land only. I live off I 81 in the Valley of Virginia and I have to go up and down hills all the time. No cruise control for me. If I am going west though and after I get to Ohio I turn it on and rarely turn it off till I get to SD. So, it has its purpose but hill driving is not one of them in my motorhome. I want to run down the hill so I do not have to hammer it to get up the other side. I can get 7.6 MPG running the mountains this way if I use Cruise the same trip is 6.9 on the silverleaf. I thought I would try it one time and it was pretty interesting. On the flat land I use the Cruise and I can get 8.1 or so. That is a 42 foot unit pulling a jeep.

Re: Cruise MPG vs Foot MPG

Reply #7 – January 08, 2011, 07:08:16 pm

Quote

RE:
"I learned really soon to keep the retarder joystick fully forward when using cruise control.
Otherwise, the first downgrade will have the cruise back-off the throttle, applying the retarder, disengaging the the cruise control. Oops."

The reason the cruise is disengaged, is because the retarder turns on the brake lights. It's the brake lights that disengage the cruise.

It is not difficult to wire a switch to optionally NOT turn on the brake lights when retarding.

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Cruise MPG vs Foot MPG

January 08, 2011, 11:25:22 am

Re: Cruise MPG vs Foot MPG

Reply #1 – January 08, 2011, 11:34:50 am

Re: Cruise MPG vs Foot MPG

Reply #2 – January 08, 2011, 01:36:28 pm

Re: Cruise MPG vs Foot MPG

Reply #3 – January 08, 2011, 02:08:54 pm

Re: Cruise MPG vs Foot MPG

Reply #4 – January 08, 2011, 03:23:15 pm

Re: Cruise MPG vs Foot MPG

Reply #5 – January 08, 2011, 03:26:13 pm

Re: Cruise MPG vs Foot MPG

Reply #6 – January 08, 2011, 03:36:03 pm

Re: Cruise MPG vs Foot MPG

Reply #7 – January 08, 2011, 07:08:16 pm

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