| milage question
- Click HERE for Original Thread
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| wingsfan |
Hi, have a question about my gas mileage. I do not know what the problem is but I get a reading of 18.7 mpg city or highway no matter what. The maintenance is all up to date and use premium gas. The only thing I can think of is when the prices were astronomical at one time, I did use regular gas for a period of time. Wondering if I screwed something up by doing this? Any suggestions would be appreciated!
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| frostyra |
| It sounds to me like you're not resetting your trip computer to "0" every time you fill your tank. Your constant 18.7 sounds like the overall average since you got the car, which seems about right. When you reset, your mpg will start at 0.0, rising fairly quickly as you drive -- that's when you can really see the effects of hot-rodding, and of babying it. After 30 miles or so, the effects are much slower. |
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| xcel |
Hi Wingsfan:
___Are you resetting the mpg meter after every tank? It sounds like you are letting it continually run and if so, imagine you received a 17 mpg tank over exactly 300 miles (17.647 gallons) followed by an 18, 19, 20, 21, 22, 23, 23, 22, 21, 20, 19, 18, and finally a 17 mpg tank all over the same 300 miles each time. That is 4,200 miles and a 20 mpg average with exactly 210 gallons of fuel purchased.
___Now let’s add in an 18 mpg average tank over the next 300 miles which means you purchased 16.66 gallons of fuel on this last tank. If you did not reset the fuel economy meter from the 20 mpg that is currently showing, you now have traveled 4,500 miles on 226.66 gallons of fuel and the display will show 19.9 mpg (19.85 actual calculated). A very small change will have occurred for an 18 mpg tank amongst the 20 mpg average over those first 4,200 miles.
___Let us take this one step further. Let us say you averaged 20 mpg over 50,000 miles and never reset the display. That means you have filled your MDX w/ 2,500 gallons of fuel. Now let us say you had a real bad tank in bitter 0 degree weather while driving around town and only received just 14 mpg actual over just 250 miles before you had to fill up. On the fuel consumption display, you will still show exactly 20 mpg!
___Here is how it works …
Given the 50,000 miles previously traveled + the 250 miles on the last tank = 50,250 miles
Divided by
2,500 gallons purchased from all previously filled tanks + 17.85 gallons on this last tank = 2,517.85 gallons
= 19.957 mpg. Your display simply will not change as it doesn’t have that resolution so it will still show exactly 20 mpg!
___The farther you travel since last reset, the less a single tank + or - will affect what mpg displays unless you actually do reset it after each and every refill. The MDX does not have separate lifetime and segment mpg display(s) but if you do not reset the segment, you will show lifetime or at least the average mpg of all tanks since the last time you reset it. Clear as mud, right?
___Although some FCD’s will reset a segments miles traveled at 2,000 miles, the FCD still displays the actual mpg since last reset. I am not sure if the X does this since I reset it at every fill. When I get the chance to fill it anyway …
___Frostyra, sorry for over running your post.
___Good Luck
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| wingsfan |
| Thanks so much for your replies; it was easier than I thought. I guess I should pull out the owner's manual and give it a good read (not my forte'!) |
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