I've been known to have a Fit or 2 .

 

Last fill-up of my LX 6-Manual, 50% city, 50% highway and some pretty aggressive accelerating around town. Used AC very little:

273.4 miles / 6.619 Gallons = 41.3 MPG .... seems like it's getting better!

SilverEX15: My experience is that the calculation has always been less than what is displayed by the computer, but not by much and still much better than advertised

 

Yep, same here. Mine seems to be about 2 MPG or 5% lower than what the car says. Here's my latest fuel up. The car calculated 41.7 MPG, my calculation was 39.4 This was 60% highway driving (cruise on 70 MPH) and AC was on probably 75% of the time.

 

My last fillup got me 41 mpg (car computer said 39.x). More highway than in-town; Eco on almost all the time; AC on all the time.

 

Wow, that is nice!

 

Another tank in the books, and my first one over 350 miles in a single tank. I got to the station with 4 miles left on the range meter. The fill up was only 8.97 gallons though, for an MPG of 39.9 (car's computer showed 42.0). Pretty consistent with my other tanks, just slightly better, probably due to a little more highway miles. I did use the AC more this tank though.

 

 

Creeping up to 31.0 average at 450 miles (per the computer). Much improved!

 

Im doing alot of city driving and not even getting any where close to 33.. 30 at most

 

That's where the hybrids have the advantage. They shut down at red lights. If I'm stopped for a freight train, or something I know will be a long delay, I'll shut down the engine.

 

If i do a tank of all city driving I am lucky to get 28-29 but mix in some urban or highway and it recovers into the 30's quickly.

 

That's exactly how I drive and why I am happy about breaking 30, BLXFITTY. Imagine if you were doing the driving in something less efficient!

 

car has just under 200 miles after the first 24 hours of ownership. picked it up with 15miles and did my first fillup today.

36.5 mpg calculated. better then i thought, but i wish the tank was bigger.

 

but isnt it rated 33 city?

 

"City" is very difficult to define. How heavy is the traffic? How often do you get stuck at a red light? How long are the red lights? There's Manhattan at rush hour and Manhattan at 8:00 AM Sunday morning.

When I go into town, I get there before 9:00 AM, and the traffic is almost non-existent. If I go on a Saturday afternoon, I mostly idle behind other cars.

 

My most recent tank was 44.04 MPG and the vehicle gauge said 45.2. 60% highway driving, AC off about 75% of the time, ECON on about 85% of the time. Driving slow, trying to hypermile, almost always keeping the Eco Ambient meter green and seldom letting it turn dark blue.

The vehicle gauge was 3.5% optimistic for that 45.60 MPG tank, and 2.6% optimistic this time.

 

I think a lot of the discrepancy between the mileage estimate and the actual math has to do with how the tank is filled. The car measures the actual fuel that passes through the system, so it should be totally accurate. I bet if you had as accurate a reading from the gas pump, the math would give a slightly different result. For example, I might get 9.298 gal, and I enter it as 9.2. If drove 405 miles, I could get an MPG figure of either 43.5 or 44.0, depending what figure I used to divide.

I'm thrilled to be getting this great mileage. I was hoping for upper 30s. This is more like Prius MPG for a much lower purchase price.

 

That doesn't make sense. Measuring MPG by tracking how much fuel you pump is going to be the most accurate figure possible. If a new car rolls out of the factory, and you add one gallon of gasoline, then drive 50 miles until the engine stalls, then you know 100% for sure that your car got 50 MPG regardless of what any instrumentation is telling you.

If you intentionally use a less accurate figure in your calculation, like 9.2 when you actually pumped 9.298, then of course this will skew the accuracy of the calculation. That doesn't make the guage more accurate than basic math. It possibly makes the gauge more accurate than flawed math.

In the above example, if you pumped 10 gallons of gas but the vehicle calculated that it consumed 9.9 gallons, which is more likely to be correct? Did the gas pump cheat you by .1 gallons, or is your vehicle's method of calculation fuel consumption less accurate than the gas pump's? I would guess that the fuel pump is not cheating you, because if you filled up a plastic fuel can, it would be immediately obvious that the fuel pump does not match the lines on the side of the fuel can.

The vehicle gauge uses many sensors (RPM, injector duration, injector flow rate and speed). The tank calculation only uses the speed sensor to calculate the distance, and the gas pump's volume reading. Four sensors introduces more margin of error than two sensors.

I have also heard that coasting for long distances can confuse the vehicle gauge.

Why Your Trip Computer Isn
Your Fuel Economy Gauge Is Fibbing

Quote from the second link "Steve Mazor, chief auto engineer for the Auto Club of Southern California, has a different explanation for the consistently high readings for the fuel economy gauges. The gauge "assumes it is a perfectly operating vehicle — and it isn't." For example, he says fuel injectors can become clogged and not deliver as much fuel as the gauge assumes."

 

Nonsense! MPG is based on fuel used, not fuel pumped.

 

Yes. And the most accurate way to calculate fuel used is to measure how much fuel was pumped into the car. Those two links at the bottom of my last post are articles which explain why the car is not as accurate at calculating how much fuel was used.

Here is another link that has a good explanation of variables that can throw off the vehicle gauge, but would not affect the pump calculation at all.

MPG Accuracy

Quote from link:
"The most accurate fuel estimates occur in vehicles equipped with MAF sensors. Vehicles which use the lower cost MAP sensors have less accurate results. However, vehicles with MAP sensors can provide reasonable results when Volumetric efficiency and injector cutoff are enabled and proper calibration is performed. (Please see the user manual for details) Much of what is discussed below applies to MAP equipped vehicles and less so for MAF equipped vehicles.

The estimate of fuel usage is ultimately only as good as the data received by UltraGauge. Each of the various engine sensors has associated errors. For example, Engine temperature may be +-5 degrees and the accuracy may vary over the temperature range(AKA non linear). Also, the sensor data may have poor granularity. For example, the OBDII Mile Per Hour(MPH) data has a granularity of 0.62 miles/hour. So the possible values are 0.62, 1.24, 1.86, 2.48MPH, etc. If the vehicle was traveling at 0.9 MPH, the value presented to UltraGauge could be either 0.62 or 1.24MPH. In this case, the value has potentially significant error at low speeds, and much less at high speeds. The errors associated with each sensor can combine and the resulting accuracy can be very poor. We have seen results as accurate as 0.01% and as inaccurate as +-13%. Your results will vary based upon your particular vehicle, configuration and calibration.

Some fuels have Ethanol and some do not. The accuracy can change if a fuel with a large percentage of Ethanol is used after calibration with a non Ethanol fuel. For example, you may perform calibration locally where simple gasoline is available. Then find less accurate results on a road trip where only Ethanol blends are available.

Also, environmental conditions can affect the accuracy. A vehicle calibrated in summer may see variation in the winter. For this reason, it is recommended to perform the MPG calibration if the environment changes significantly. It is necessary for the Vehicle's ECM to compensate for the environmental changes in order to minimize emissions. Some vehicles compensate better than others. For those that do compensate well, the environmental variation will have a much less significant effect."