how would u calculate gas milage with a speedo that is off by 5 miles an hour . i need some help with equatio

Question

my speedometer is of 5 miles an hour slow. how do i figure out how many miles i have whent per tank by the odometer reading. there has got to be some kind of equation to figure it out.

Answer 1

You don't typically calculate gas mileage using the speedometer. If your odometer is off because of the problems with the speedometer, then I can't help you.

Next time you fill up on gas record the mileage from the odometer. Let's say it reads 20,123 miles. Record this number.

Then the next time you fill up on gas. Record how much gas you put into the tank and the new odometer reading. Let's say you put in 12 gallons, and your odometer reads 20,400 miles.

Gas mileage would equal (20400-20123) / 12 = 23.08 miles per gallon.

Answer 2

If your speedometer is off, and thereby your odometer readings, you can compensate for the error, but to do that you have to know what the error is.

You say your speedometer is slow by 5 mph, but you don't specify the conditions. Does 60 read as 55? does 30 read as 25?

actual = measured * K

If say for example, 60 reads as 55, and 0 reads as 0, then you compensate for the error by multiplying by the following scale factor

actual_distance = measured_distance * 60 / 55

Answer 3

If you want to convert your odometer to mpg, do this:

The next time you get gas, make sure you fill up all the way and reset your TRIPOMETER, the one right next to it.

The time after that, you'll see how many miles you traveled between filling up. To get miles per gallon, divide this value by the amount of gallons it takes to top off the tank. (Total Miles divided by total gallons)

Answer 4

Even better than an equation, there are calculators! =)
Try this site:

http://www.webwinder.com/wwhtmbin/java_mpg.html