A question of GAS/milage/wear-and-tear for car guys...

[Din Of Win]

So, with GAS prices going up, and my car in general disrepair, i was wondering the other day: which route can i commute on that expends less gas and is 'nicer' to my car's engine? Both routes take about the same, time wise but differ in a few ways:

1. The highway: Direct route, but all stop and go. Shorter geographic distance.

2. The back roads: Indirect, but constantly cruising. Longer geographic distance.



I tend to switch them up on a whim, but i never really thought about which one is 'better' for my car...

[Tim Cole]

2

[CrispyDelicious]

I'm no car expert, but I would think the condition of the roads should be factored in. Cruising on the back roads may be fuel efficient and more gentle on your engine and whatnot, but if they are ridden with potholes, it can do a number on the structural integrity of the vehicle; if the roads are poorly paved, then the body suffers. But just given the info you provided? 2.

[Bob Lee (QSC)]

How much shorter and how much longer?

[rhino333]

Generally speaking, I usually take the most direct route that has the least construction. I log the mileage and write it off on my taxes as expense. That being said, I wonder if a person that takes a longer route on purpose and then gets audited would be open for penalties from the IRS?

[Chebass88]

A difficult question to answer, and not enough information provided.

There are many ways to improve gas mileage, the traffic profile being only a part of it. A few ideas for you:

1. Smooth accelerations and decelerations. Always. Will impact the mileage the most.
2. Over pressurized tires (by a pound or two; for example, if the max pressure is 44, but the spec says 36, inflate to 38 to 40.). This reduces the rolling resistance, and you get better mileage.
3. No speeding. IIRC, on a highway, the optimum speed for gas mileage is 62.5 mph.

Also, I'd recommend keeping a detailed log, so you can track your progress.

[Selta]

Originally Posted by Chebass88

There are many ways to improve gas mileage, the traffic profile being only a part of it. A few ideas for you:

3. No speeding. IIRC, on a highway, the optimum speed for gas mileage is 62.5 mph.

Not true for all vehicles...
In my Mustang GT, I get the same gas mileage at 60 as I do at 70 generally. 55mph however nets more than the 60-70 range.
In my father's F350 diesel, we lose several MPG just by going 60 instead of 55 (and when you're talking 15 versus 18-19, it's substantial).
My partner's neon gets the best between 50 and 55, and drops off steep after 60.

[Chebass88]

Originally Posted by Ray Salamon

Not true for all vehicles...
In my Mustang GT, I get the same gas mileage at 60 as I do at 70 generally. 55mph however nets more than the 60-70 range.
In my father's F350 diesel, we lose several MPG just by going 60 instead of 55 (and when you're talking 15 versus 18-19, it's substantial).
My partner's neon gets the best between 50 and 55, and drops off steep after 60.

I'll agree with that. I have noticed excellent gas mileage myself in that regime, so it is relatively accurate for me. I do not have instantaneous gas mileage readings though, so my mileage estimates are averaged per tank purchased (I fill out my log & reset the odometer for each tank).

It is safe to say that travelling at excessive speeds uses more gas, and therefore decreases the mileage. The location of the maxima on the mileage vs. speed plot might differ for various vehicles, though.

[DerHoggz]

Originally Posted by rhino333

Generally speaking, I usually take the most direct route that has the least construction. I log the mileage and write it off on my taxes as expense. That being said, I wonder if a person that takes a longer route on purpose and then gets audited would be open for penalties from the IRS?

I'm pretty sure you can't write off miles from commuting.

[-Kramer-]

Originally Posted by rhino333

Generally speaking, I usually take the most direct route that has the least construction. I log the mileage and write it off on my taxes as expense. That being said, I wonder if a person that takes a longer route on purpose and then gets audited would be open for penalties from the IRS?

Any mileage you drive from home to work/first stop of the day is not tax deductible. Similarly, any mileage driven from work to home is not deductible.

On topic: I would think that other conditions being equal, the second option would be better for your car and probably gas mileage as well if the distances are not too different.

[-Kramer-]

Originally Posted by DerHoggz

I'm pretty sure you can't write off miles from commuting.

Beat me to it.

[Pilgrim]

Any stop and go eats more gas. Wear on the motor between steady cruising and moderate speed up and down is probably not significantly different provided that it gets well warmed up. There's definitely a wear AND mileage difference in hard acceleration and deceleration vs. cruising.

If you want to know the gas consumption difference, try traveling on each route for one week; begin with a full gas tank each week, fill at the end of the week. Compare. Keep all other driving as similar as possible so that you have a fair comparison.

[turbo2256b]

Least amount of stop and go driving is best for economy.
Check your front and rear wheels for drag. Brakes and bad bearings can cause this and eat up economy.
On most of my vehicles I jack the rear of the hood up to let air trapped under the hood vent. I have seen as much a 2 MPG increase doing it. New plugs can help even these days with supposedly the ability of them to last for 100K. Oxy sensors another big one. Thermostats are als overy important in todays EFI cars. If one isnt working properly it can kill fuel economy. They are probably the least persice compont in your engine being 25% acurate when new. Suggest NAPA premium ones seem to work best and longest.
Knowing what you drive could help. More info on the car in general??

[seanm]

Originally Posted by Chebass88

3. No speeding. IIRC, on a highway, the optimum speed for gas mileage is 62.5 mph.

Interesting... 6.25 mph is 100kph, the speed limit on major highways in Canada.

I agree with others, it also depends on the conditions of the roads. One bad pothole can wipe out a *lot* of gas mileage gains. That said, I would prefer a nice gravel road to the hell hole that is the main artery that I take to work every day.

[Number27]

Originally Posted by rhino333

Generally speaking, I usually take the most direct route that has the least construction. I log the mileage and write it off on my taxes as expense. That being said, I wonder if a person that takes a longer route on purpose and then gets audited would be open for penalties from the IRS?

This is a fantastic post. I feel like it would be a joke in an xkcd comic.


To OP: I face sort of the same dilemma, but since i'm going mostly against the flow of traffic it's not nearly as much stop and go. Around here the highways are usually in as much disrepair (in regards to pot holes) as the back roads. They just spent all of last year resurfacing I95 north of the Mass Pike and it already looks like the surface of the moon. Personally i'd take the back roads.

[turbo2256b]

Originally Posted by Ray Salamon

Not true for all vehicles...
In my Mustang GT, I get the same gas mileage at 60 as I do at 70 generally. 55mph however nets more than the 60-70 range.
In my father's F350 diesel, we lose several MPG just by going 60 instead of 55 (and when you're talking 15 versus 18-19, it's substantial).
My partner's neon gets the best between 50 and 55, and drops off steep after 60.

Most trucks drop in fuel economy at speeds over 55. Just not aerodynamic.

The Neon is possibly a trade off between some acceleration small engine and gearing.

[Selta]

Originally Posted by turbo2256b

Most trucks drop in fuel economy at speeds over 55. Just not aerodynamic.

The Neon is possibly a trade off between some acceleration small engine and gearing.

It's mostly due to the car being in a pretty bad shape, but not worth me sinking any amount of money into at this point, beyond changing the oil. Just going to drive it until it dies and get her something new.

[DUC1098]

The most important thing to think about when planning a route is that all vehicles will get ZERO MPG when idling. Hybrids automatically shut off the engine when stopped or at slow speeds, if possible, which is one of their advantages. So ideally you want to keep moving as much as possible. If you are going to be stopped for more than a couple of minutes it can be worth while to shut off the engine, assuming you have a good battery that can handle multiple restarts.

When you are moving, gas consumption is in MPG. When stopped it is GPH.

[Truktek2]

The easiest things you could do would be remove all unnecessary weight. Yep the SVT in the trunk has got to go. Check your air cleaner. If its dirty it will drop your mpg. Try not to drive over 55, after that wind drag goes up exponentially. No sudden starts or stops. I wouldn't raise the air pressure in the tires even though it would give you a slight increase in mpg. It would wear your tires in the middle, sacrifice handling and up the chances of a blowout. You could also try drafting the car in front of you (kidding)

[turbo2256b]

I drive an 87 Grand Marquis aerodynamicly a brick. With mods using factory parts it got 27 to 32.9 MPG. This was at speeds from 55 to 90 crusing. In town 20 to 22. Tires are 275 50 15s front and 295 50s rear. Parts from that engine are going in another 87 soon to be daily driver. The current engine is carbed and has dual quads on it and gets 18 MPG at the same speeds. Currently my daily driver.