MPG solution

eyes2east · 10-12-2004, 11:59 AM

Hey guys!

I have been getting 12 mpg in nearly 100% city driving in my Titan. Recently I started driving with the VDC off and it has gone up to 13-14mpg. So I saw some improvement there. However this past weekend I had to drive to Birmingham so this was my first chance to get some highway driving mileage. By accident I discovered my speedometer is off (slow). I am losing about half a mile every ten miles. If I drive 300 miles before filling up adding back the half mile every ten miles that equals 315 miles. That essentially adds 1 more mile per gallon. Do you guys think that maybe others on this board, like myself, have a speedo problem and are getting better mileage than they think?

Blizzard · 10-12-2004, 12:06 PM

You mean the odometer and not speedometer, right? I remember somebody posting awhile back that theirs was off as well. If I remember, I'll check mine on the way home tonight.

TriKKy · 10-12-2004, 12:06 PM

What makes you think that it is your speedometer and not your odometer. I know for a fact that my odometer is off by 10% in my favor, so you won't hear me complain about it. For every 1 mile I go per any highway milepost, my odo reads 0.9

Doghouse · 10-12-2004, 02:59 PM

I checked my speed the other day. At 80kph, I was doing 23.8m/s via gps. 23.8*3600=85680m/h or 85.68Kph. Just a slight difference! 49.71 vs 53.24 mph. That explains why I was picked off for those speeding tickets.

Markus · 10-12-2004, 03:15 PM

Quote:

Originally Posted by TriKKy

What makes you think that it is your speedometer and not your odometer. I know for a fact that my odometer is off by 10% in my favor, so you won't hear me complain about it. For every 1 mile I go per any highway milepost, my odo reads 0.9

So....wouldn't this underestimate mileage by about 1.5 mpg?

TriKKy · 10-12-2004, 04:49 PM

Quote:

Originally Posted by Markus

So....wouldn't this underestimate mileage by about 1.5 mpg?

Yes and no. How much it affects it depends on how far you are going. For instance, hypothetically, if you are lead-footed and get 250miles/tank you really went 250 + 25 = 275miles / 25 gallons to fill (let's say) = 11. If you calculated off of the original 250 it would be 10, a difference of only 1.

If, however, you go 300 miles and fill up with 25 gallons you would be at 12. But in this case if you correct for odo error it would be 330/25 = 13.2 a difference of 1.2. The lesson here is basically that a larger amount of miles driven = larger error = bigger difference in calculated MPG.

Boone-Titan · 10-12-2004, 06:40 PM

If the 1 mile gain in 10 driven is correct, it would be 1.1*M/G=MPG. Linear relationship.

Doug · 10-12-2004, 06:58 PM

Just do what any person can do . Go buy the Tornado and install it in seconds with only a screwdriver. Garanteed 2 to 4 mpg increase...Doug out.......................

mickeysfan · 10-12-2004, 07:42 PM

Doug, I got the tornado I didn't pick up any MPG. If the tornado "spins" the air wouldn't the air get "broken" up once the air hit the mass air flow sensor??

pciley · 10-12-2004, 08:17 PM

Another victim... could have put that $$ towards a good wax job or K&N drop-in.

mickeysfan · 10-12-2004, 09:11 PM

Well, not quite, I made Pep Boys give me a thirty day warranty to test it out. I simply removed the Tornado and returned for a full refund. I noticed NO increase in MPG.

Carrot Top · 10-12-2004, 10:51 PM

I have noticed also that my odometer is reading short. Mine is under about 4% under. Now when I fill up and calculate my MPG I just take my mileage and add 4% then divide by gallons used. This gets me actually MPG. It also makes you feel a little better about the Titans gas mileage. The best I have gotten is 17 on Hwy with no load and the tail gate down. The worst is 8.5 towing a trailer in a head wind. I'm avg 13 in city. Bought truxedo bed cover from Jamie and that helps both city and hwy.
I have CC LE with Big Tow Pkg and Off Road Pkg.

TriKKy · 10-13-2004, 07:00 AM

Quote:

Originally Posted by Boone-Titan

If the 1 mile gain in 10 driven is correct, it would be 1.1*M/G=MPG. Linear relationship.

A linear relationship does not mean that the difference is always the same, it just means the difference grows in a linear fashion.

eyes2east · 10-13-2004, 07:09 AM

Thanks for all the input guys!
I am not so upset at the mileage now and I get the bonus of using less miles towards my warranty!

IMADOGMAN · 10-13-2004, 08:04 AM

[quote=Carrot Top]I have noticed also that my odometer is reading short. Mine is under about 4% under. Now when I fill up and calculate my MPG I just take my mileage and add 4% then divide by gallons used. <clip

I just returned from a 1700 mile trip, and I have to agree with Carrot Top. My odometer is off by 4% also. Every 100 miles on the odometer is actually 104 actual miles. My best tank on this trip (75-80 mph cruising on various terrain) was right at 17 mpg. Average was probably closer to 15.5-16 mpg.
Those calculations are without adding the 4%, so they will be a bit higher.