Gas mileage, shifting into overdrive between 30mph-40mph, and cruise control

My father seems to believe that getting the car into high gear as soon as possible saves gas. He has a new ford focus with 30,000 miles on it all driving in this manner. Observing him drive you will see him shift through all the gears but he ends up in overdrive at 30mph-40mph and sometimes below 30mph. He does this and in addition uses the cruise control in city streets between lights. He claims it saves gas. My dad is a honest environmentalist and has good intentions. But I try to explain that laboring the engine like this does not save gas and pollutes the environment more by building more carbon. Am I right or is he right? He always references this show “as a matter of fact.”

In general shifting to high gear sooner rather than later saves fuel, but you can take it too far, and he has.

If he’s lugging the engine he’s doing more harm than good.

Cruise control is meant ONLY for highway driving, not city streets. In the city cruise isn’t saving anything, and it’s not safe.

Good luck trying to convince him, though. He’s a true believer.

If he’s in top gear at this speed and he gives it some gas, does the car accelerate smoothly without any strange noises? If not, he’s lugging the engine. Lugging the engine can cause damage that costs way more to fix than the pennies he’s saving on gas.

Yes, the engine luggs. I hear the belts make noises also, and a rattle off the tailpipe from the vibration. Also, his adjusted gas millage went from 43 mpg max when it was new down to 41 mpg now. This of which he attributes to cold weather. But I think its possible he is building carbon in the exhaust system. If this is true could this bring down millage, and by driving this way will it continue to depreciate mpg?

Carbon is not the problem. Forget carbon. A 2 mpg decrease is easily attributable to colder weather.

Dad is lugging the engine, and that’s not good. He’s probably using MORE gas in fifth gear at 35 mph than he would in forth, but good luck convincing him.

It’s his car, let him break it if he wants to.

His intentions maybe good but the owners manual should disagree with him on the safe use of the cruise control and shift points. Some of us, me included suffer from the “if a little is good, more must be better” syndrome. As you explained it, I believe you are right and we older folk need to trust our kids as they mature and begin showing more concerned for our welfare.

First I am surprised that cruise control works below 40 in a ford. For my fords it hasn’t including my 2003 taurus. The car is a manual? Then any kind of jerking or rocking means the gear is too low, assumeing the engine is well tuned. The risk is wear on the pistons and the bearings thereof. OD below 35 even on a flat or down hill is too low check owners manual. If he will not follow the owners manual then really frankly it is his car.
The milage issue is trumped. We each believe what we wish to. Since its your dad … If he really listens to the show then he should relisten to a mix tape/cd of the times the advise has been no jerking or rocking thats bad. I have heard this advise to others many times in the last twenty years I have been listening.

I’ve had one Ford/Lincoln/Mercury car that the cruise control would work on down to 25 MPH. The other Ford/Lincoln/Mercury’s cruise controls would all work down to about 35 MPH.

It’s a hard call. I just come off as a smart ass when I question it. Funny thing is, is that I can’t remember him driving like this when I was younger. When I was a kid we had stick shifts all the time. But then gas went way up, and this focus came out, he started driving like this. I am curious to what would break in the future if this driving continues. I should just turn my head, but it frustrates me to see him rag on this car everyday and ruin a fine automobile. He has talked about trading it in for a fusion hybrid. If it is not ruined by than I said you will have to get a automatic. An automatic because I don’t think fusions have stick shift in hybrid.

While it sounds to me like he’s shifting too early, it’s also true that it is folly to continue to attempt to help someone who has already declined to be helped. Unless he’s asked for your advice, love him for his strengths and accept this minor weakness. It’s his money, it’s his car.

In the bigger scheme of things, this thing is insignificant.

"The car is a manual? Then any kind of jerking or rocking means the gear is too low, assumeing the engine is well tuned."
Don’ you mean the gear is TOO HIGH?

“I am curious to what would break in the future if this driving continues. I should just turn my head, but it frustrates me to see him rag on this car everyday and ruin a fine automobile.”

I was completely with you til you referred to a Ford Focus as a fine automobile.

You both may be partially correct depending on the definition of “early” but I have reservations about his use of the cruise control. Your and your father’s difference of opinion would be quickly resolved if you had a vehicle with an instant gas mileage readout as do our 08 and 09 GM cars. This feature should be mandated to give people a fair chance at saving gasoline. The DIC (Driver Information Center) on our less expensive car includes tire pressures, average fuel mileage, instant fuel mileage, Trip A miles, Trip B miles, oil life remaining, engine temperature, total miles and outdoor temperature.

Yes, you can shift too early for good gas mileage but I will not even try to tell you what speed that must be for your particular vehicle and in addition, the gas pedal position has an immediate effect on instant fuel mileage. I have easily found speeds and traffic conditions where 4th gear is equal to or more economical with gas than 5th gear using a manual transmission.

Generally, lugging the engine in 5th gear may very well be less economical with fuel than letting the engine run a little more freely in 4th gear but the difference much depends on your perceptions of lugging and running freely.

You are right, he is wrong.

He may be combusting fewer times, but I’m pretty sure each power stroke uses more fuel. He’s also putting a lot more stress on the internal engine components, and he could (he WILL) have a bearing fail, or he could even bend or break a piston rod. Oh, and he could be wearing out the transmission faster, too.

As long as when he gives it more gas it still accelerates immediately and smoothly, he’s not keeping the RPMs too low. If you can feel the car shaking, he is keeping the RPMs too low.

He needs to stop this right now.

My dad took abysmal care of his cars. He drove them until they broke. He rarely changed his oil unless the light came on. He never washed them, never waxed them, and didn’t have the greatest technique with a clutch.
On the other hand, they were his cars and it was his money. He just never really cared about his cars.

My dad’s been gone for some years now. I miss him very much. And I realize now that this thing that I criticized him for, this lack of car care, was really unimportant. Don’t try to change him. Enjoy him. Don’t make your years together filled with criticism. Make your years together filled with enjoyment of one another. You’ve offered your advice, now offer only your love.

Sorry to lecture. If doing so causes you to refocus even a little bit earlier than you would have otherwise, I’ll take my lickin’.

You are right,don’t sweat it-I’ve been around a lot of old timers who drove like that,on the other hand I’ve been around kids who had tach the engine out in every gear going down hill (the old 3 on the tree vehicles weren’t to smooth like this)-Kevin

Yes thats right rpm too low gear too high.

I had the same idea. Cars are things, life is.

thibo, I agree with what you say except I doubt if lugging an engine creates any more polution or carbon.