I was reading on a 2nd gen Facebook group about how you "can't go by the MPG readout on the dash and have to track miles and how much gas it used". The 2nd gen gas tank uses a rubber bladder, and I was under the impression you can't calculate gas usage the "old school" way because if it's say 67 degrees when you filled up last, and 87 degrees when you fill up again, the amount of gas the rubber bladder can hold will change.
The bladder tank can definitely skew the calculation of a single tank, but over multiple tanks the variations will inherently cancel out. Calculated is still your best bet. In my 3rd gen experience, the mpg displayed in-dash is ~7% “optimistic”. Gen 2 I’d suspect is similar. AFAIK Gen 4 continued this tradition. For Gen 5, just from what I’ve read here, Toyota finally is keeping it honest.
I disclaim that my experience comes from gen 3 and gen 5, but I have found that there is probably intentional inaccuracy in the gen 3. The computer system is capable of high accuracy in speed measurement for the purposes of operating the hybrid system. But regulations allow a 5% tolerance on the speedometer/odometer, and Toyota uses this to its advantage. This yields slightly better fuel economy, and it shortens the warranty coverage period (by 5%). I was able to verify this by timing my speed on a test track. The speedometer reads 5% higher than actual speed. I have not observed this in my gen 5.
Don't conflate speedometer variance with the odometer accuracy. Regulations do not allow "5% allowance in the odometer", and if Toyota was doing that, they'd be in court in a heartbeat. Honda got spanked for just that, a few years back: https://www.cbc.ca/news/honda-canada-settles-class-action-suit-over-odometers-1.860237
The bladder don't have much to do with mpg me thinks. Once you start filling and driving a gen2 regularly you'll stretch that bladder in 5 months. I went from filling 15 min at pump to a 2.5 min fill up in this time this is unassisted filling me setting lever and watching went from placing lever cutting off at 2.8 gallons or such . To wet 8 can drop 8.4 in 3.5 min or less standing they're . I do it several times a week at Sheetz only blue fuel
What's extra funny is that the exaggeration of the speed is clearly just built right into the speedometer. If you use an OBD scan tool and view the vehicle speed PID reported by the skid ECU (which is the value the speedometer relies on), it's accurate. And the speedometer display is digital, not any kind of approximate analog movement. So it's pretty clear there's some line of code in the combination meter that takes the accurate value from the skid ECU and multiplies it by 1.05 or something to exaggerate it for display. I'm not sure that's necessarily the same value used in MPG computation though. Inaccuracy in the MPG computation may have other sources.
I was able to verify at the time, that auto manufacturers were allowed a 5% tolerance on the accuracy of speedometers and odometers. As I said, I don't know if it's true any longer.
I have a Gen 4. I have noticed broad variation in MPG ratings between segments of errand running around town...one segment will report 60 mpg and another 30 mpg , etc. On long road trips, I've noticed the average mpg tends to increase significantly as the miles progress. On the whole, the average runs about 59+ mpg.
One reason to care, you've already mentioned twice: "if it's true any longer." Knowing where you had found the relevant law or regulation would allow me or any other curious reader to check that. If the law or reg now says something else. that would also allow knowing (as such things normally show version history) whether it has changed since you looked. (We might not know exactly when you looked, but it was "when [your] gen 3 was new", so it's a practical interval of history to search.) When I look such things up, being in the US, I often look in US laws and regulations, which may or may not be similar to those in other places. As your profile says Canada, it might be likely that you were looking in the Canadian equivalents. Though you also might have been looking at something else, like a document of some transnational standards body (which may or may not have been adopted by the authorities in any given nation). Information on where you looked would help PriusChat readers, who may not all live under the same laws and regs you do, in determining whether what you found or say you found also applies in their part of the world. There are a lot of good reasons for PriusChat readers to care about the sources of things they read on PriusChat.
Google: What would happen if an automobile manufacturer were found to have 5% inaccurate odometer the AI summary is interesting.
So we're saying all odometers in cars have no variance and they're not inaccurate at all and. No allowable tolerance and that's that ,?? Interesting
