truelies

I calculated the MPG by my own between two refuels. It's only 23miles/gallon, but the RDX computer says 24.8miles/gallon. So it's not accurate.

I never saw a forum limited the time that you can edit your post!

justnspace

iTrader: (1)

LOL @ this guy.
the MID is truly lying to you.

LuvMyTSX

It's known to be off by a small amount. At least it's only off by about 1 mpg and not 5 or something.

I always calculate it myself anyway.

discovermac

most likely, your calculation is off a bit. wait a few more fill ups then average it all out - one to two fill ups would not give you a fair assessment. in my case, i have my own and the mid is +/- 1-3% at most difference per fill up (and quite close to lifetime mpg)

Carbon2008RDX

The best MPG I've gotten to date according to the MID on highway is ~23 and I've had my RDX since June 2008.

Mr Marco

It is 15 Min, SUCKS, I wish we could delete or change our shit like CrackBerry.com.
I'm at 18-19 MPG, but I drive like an Italian.

mrgold35

I've never figured out how the mpgs were calculated on the MID for my TSX or RDX. What is the trip B average mpgs say? My trip A mpgs can sometimes be higher or lower depending on how I drive between fill-ups compared to my trip B; which I never reset.

The only other thing I can think of is the gas pump my be off and you are putting in less gallons indicated on the pump. I think 20/20 or 60 minutes did a story on gas stations cheating folks this way. The pumps are not calibrated correctly and you put in 10 gallons and they charge you for 11 gallons or more.

Try the same test with another gas station. The most I been able to put into the RDX was about 17.1 gallons with my DTE at 20 miles. If you can put in more than 18 gallons, then you know the gas station pump is not calibrated. Doing your manual calculations with 13 gallons/300 miles=23mpgs compared 12 gallons/300 miles=24.8mpgs is about a 1 gallon difference.

truelies

I used the same pump in same gas station. So it should be accurate. Don't know how did the government test mpg of this car, maybe they didn't count the turbo in?

justnspace

iTrader: (1)

are you filling up when you reach empty? the tank has 2 or 3 more gallons after it reaches E. this is an inconsistency and will cause your calculations to be off by 1 or 2 mpg. are you rounding? do you know if the computer rounds? this will cause an inconsistency with your calculations. As you can see there is a lot of things that can affect your calculations. Unless you have everything controlled, I say the MID is pretty accurate.

truelies

I don't think 2 or 3 gallons left matters. The MID displays miles, I divided it with how much gallon I refilled. I didn't round.

mrgold35

Are you topping off until you see gas in the tank OR just letting the pump click off when full? I can always put in 1 1/2 to 2 1/4 gallons in my RDX or TSX depending on the pump. I have to let the gas trickle in and it takes about 5 extra minutes to add the extra gallon or two of gas.

Unless you top off and see gas in the tank, I don't think any manual method of calculation will be as accurate compared to the MID.

truelies

Let the pump click off. Same pump, so last no extra gallon added, then this also no extra gallon added. Why you think we need to full the tank for an accurate calculation?

mrgold35

When the tank is full and you can see the gas then you know how many gallons divided by mileage for your average. When you let the pump click off, there is no way of telling if you are short 1/4 gallon or 2 1/4 gallons for your gallons divided my mileage calculations. I think the best you can hope for is you are consistently making the same error in your calculations compared to the MID.

Instead of trying the Miles driven/# of gallon = average mpgs, try:

Miles driven/average mpgs = # of gallons (you have the # gallons on the pump, compare 24.8 to 23 to see which one gets you closer to actual gallons pumped)

300 miles/24.8 mpgs = 12.096 gallons used
300 miles/23 mpgs = 13.043 gallons used

OR

Average mpgs X gallons = miles driven (to double check the number of gallons pumped X MPGs equal the mileage driven)

24.8 mpgs X 12.000 gallons = 297.6 miles
23 mpgs X 12.000 gallons = 276 miles

I think the big unknown is the number of gallons used.

truelies

So you think a same pump can short 1/4 gallon this week and short 1/2 gallon next week after click?

mrgold35

NO, I'm saying the pump is 1 gallon short (for example) every time you fill up and it clicks to stop. Instead of you doing your calculation with 13 gallons to top it off for 300 miles driven, the pump is only giving you 12 gallons at the click for 300 miles driven. You don't know how short you are when it clicks off. It could be 1/4 gallon short or 2 1/4 gallons short. You will not know until you fill your tank until it clicks and then fill it up until you see gas to know how gas you put in after it clicks.

I think the manual calculations are using incorrect numbers. That is why I suggested using the same formula differently to see if you get the same results to see if the MID or your manual calculations are correct.

Either the MID is off AND/OR the manual calculations are off AND/OR the gas pump is not calibrated correctly.

truelies

I see what you mean. But this means the pump displays like 13.5 g, but only give me 12.5g. Just wondering if this is illegal? The pump allows to be made so inaccurate?

LuvMyTSX

I have heard of shady gas stations doing this to make more money, but yes, it is illegal. They should be calibrated correctly, but whether they are checked often or at all, who knows.

I thought you weren't supposed to top off gas tanks? I was under the impression you were supposed to leave it when it clicks off. I think this is for emissions purposes - if you fill it up too much, it just goes into the atmosphere as vapors or something... I could be wrong, but I remember hearing/reading that somewhere.