Does anyone out there have confirmed information that the newly manufactured Prius's have there MPG guage updated to reflect a more accurate reading. Our Prius was the first to come off the line back in May 2009, and currently approaching the 14,000 mile mark. The guage has been consistenly off by 2-3 MPG from the beginining. I believe some of the newly manufactured Prius's have a more accurate reading than earlier ones. Can anyone out there with a newly manufactured prius confirm this. alfon
Mine was built in Sept. My gauge was dead on when I did my calculations on a recent 720 mile road trip. I can't confirm nor deny, just saying what I found.
Very interesting. I wonder if they patched/fixed their software. I will have to ask my dealer when I bring it in for the OCI. Have you been able to check your speed readout say to a radar gun?
MPH is off about 1 mph at 55 mph. And the only time I have checked gas mileage against the HSI I was off just a hair at 1.1 mpg. That was at the first click of the nozzle BTW. Manufactured May of 09.
The speedometer is not relevant to the consumption display. The speedometer reading that is displayed is always going to be fast because of the UN regulation on speedometers. The ODB knows the true speed of the car, a ScanGauge will display the actual speed. The consumption display uses fuel flow to the injectors and distance traveled, not speed. The consumption display is also off but not because of any regulation, it's off because Toyota marketing decided it could fool the customers into thinking the car actually got better mileage than it does. They didn't think some owners were actually smart enough to figure out what they had done fairly quickly. If it has been fixed on later cars that's very good but it's most likely as close as they will ever come to admitting that they made an error in judgment. I will be pleasantly surprised (very surprised) if they call in the earlier cars and offer to fix the problem.
Is there a TSB on MPG/ODO deviation. I assume they would not jack with MPH. ScanGauge is close enough for me. I also do the calculation every time I fill up. None of the three match or even come close all the time. Mostly the SG and calculation are the closest.
It's not "broke", they aren't going to "fix" it, it works exactly as intended, and I bet 95% of owners aren't smart enough to know any better.
Of course its not broke. Its just wrong. If the gas gauge was calibrated incorrectly, it would not be broken, just wrong. I bet they would fix that, well, maybe not. In software, it is called an "undocumented feature."
July '09 manufacture date and MPG gauge consistently 1 - 3 mpg high relative to fill-up calculations. Comments on Fuelly.com indicate this is common. Calculations and MPG gauge should use the same distance data so that does not explain the difference. Measuring accurate fuel flow is an inexact science which requires fuel specific gravity, temperature, flow correction adjustments, etc., etc., etc. I imagine the flow meters used on cars are cheap and inherently inacurate (my BMW's MPG gauge is also 1 - 3 mpg high). While the gauges are not accurate they are useful as relative indicators of fuel usage which is probably all they were intended for.
I now have over 2,700 miles on my GenIII. I fill up once a week, every week since taking delivery in August. Every week the difference between the measured and computer generated MPG is 2-3 MPG, with the measured value always being lower, but always higher than the combined EPA number of 50 MPG. I now have a high degree of confidence that when the diplay says I'm getting 54 MPG, I'm probably getting closer to 51 or 52 MPG. As stated above, there are errors associated with both the measured and displayed MPG figures. So what? Is this really a big deal?
That has been my experience with my G3, IV. I downloaded (off this site) an Excel chart someone made. With 6600 miles, my actual is consistently 2.1 mpg lower than the indicated. With that knowledge, I can live with it. Sure, I wish it were perfectly accurate, but being consistent is better than being inconsistent. Few things in life are perfect. That is especially true with automobiles; media reports; politicians; and etc.
It may be as designed, but it is misleading, especially since one of the selling features of the vehicle is good fuel consumption. Hyundai had a recall and had to offer longer warranties to customers because they misrepresented the displacement on their Sonata engines (and not by much either). If it was "within 5%" but varied from car to car and tank to tank, sometimes low, sometimes high, it might be ok, but it is consistently 5% high, and if this was intended, makes it a purposeful misrepresentation.
