A fuel economy question


#1

My wife and I are having a discussion about this subject. We live in Astoria, Oregon. Astoria is at the mouth of the Columbia River and is located on a peninsula. To approach Astora from the South you must cross a bridge. The question is about which approach to our home uses the less fuel. We live on top of a hill in Astoria at 342 feet. The bottom of the hill is at like 10 feet above sea level. The southern route is more direct, but the grade is steeper. My wife feels that it is best to drive at sea level around the peninsula and approach from the North-east where the grade is less steep. The difference in mileage is about .8 of a mile. We drive a 2002 BMW 525I that gets on the road about 27 miles per gallon when I baby it. So the question is whether the shorter steeper grade uses more gasoline than the longer less steep grade does?


#2

Can’t anyone do math? Driving 0.8 miles (the longer route) burns a mere 0.03 gallons if gasoline. Even at today’s prices that’s about 12 cents worth of premium fuel. If the shorter, steeper route requires a lower gear, you might give back some of that 12 cents. Maybe as much as 8 cents!

So you sir, should take the steeper road every time and chastize your wife for throwing away 4 cents of the family fortune each time she goes the long way 'round!

Um, if your car doesn’t downshift at all, your savings might even double to 8 cents per trip.


#3

Under normal conditions the longer trip will use the most total fuel, but it will be better mpg. So the long trip might cost $1.27 and get 25mpg and the short trip may cost a total of $1.22 but only get 24 mpg (you will be traveling less miles). It real life different cars will have different characteristics and different drivers will as well, so it is difficult to say for sure about any specific situation. The return trip also may be different and there is no easy way to make sure which is cheaper.

My money would say likely about five to one the short trip will be cheaper either way.


#4

One way must be safer than the other. I would take the shorter route and not care about how much difference there is in fuel economy. I had an old Mazda truck that seemed to like really steep hills in second gear. I spent an hour doing that and didn’t notice a decrease in mileage. Strangest thing.


#5

The engine does the same amount of work climbing from 10’ to 342’ whether it is steep or not. So, the longer path uses more fuel unless there are other considerations, like stop signs, more traffice, etc. Joseph is right.


#6

i would say it would depend on whether the transmission has to down shift to go up the steep hill… also, which way has less stop light/stop signs?

you must be up around astor monument to be that high. near the H.S. i would bet?

any way. at .8 of a mile difference, the down hill jaunt would depend on how much you use brakes, and wear and tear on them too. again this would depend on the stop sign/light number.


#7

When you drive go the way you want and have the wife do the same thing and do not worry about 12cents


#8

neither way has any stop signs, but the shorter steeper route does have more intersections that you have to slow down for.

You must be familiar with Astoria? We live to the west of the Astor Column our location is right above the Astoria-Megler bridge to Washington.


#9

Have you ever discussed travel routes with your wife?

She: Why did you go that way? It’s longer. I never go that way!

He: It just doesn’t matter to me for that short a distance.

She: But it’s shorter my way…

And on, and on, and on…

Eventually, you go her way or tell her where to get off. Then you go her way.


#10

Eventually, you go her way or tell her where to get off. Then you go her way.

Let’s ask Tommy. He’s good at that kind of stuff!


#11

I would take the short way up to use the least gas and the long way down so that I wouldn’t have to ride the brakes to keep my speed in check.

When my wife wants my opinion, she tells me what it is.


#12

I have been experimenting with mileage fro over 10 years. The three cars I have had in that time have all had DIC devices that give me instant and average gas mileage. They have proven to be extremely accurate. I drive two hills during my comute. Both are approximately 2 miles long but one is significantly steeper than the other. The best I can do on the steep hill is 14 mpg, good momentum at the bottum and running in 3rd gear. The other hill which is less steep and according to google contour maps raises the same elevation, I get just over20 mpg.
You will have to do the math to see which is less expensive to negotiate. Just one other point. When I run the car in 3rd gear the engine turns more RPM’s but it works so much easier because there is more power available to the drive wheels. I have found this to be more efficient than making the engine work harder in a higher gear at lower rpm’s. Thoughts?