What is your DTE after fill-up? (Gen 5)

Lol.

Bro, if you aren't absolutely clear on how high heat + AC affects MPG then... I don't know what else to tell you.





Here are two individual trips on a decent day (80's) when I don't have to use my AC. This included city and some highway driving.



Here's the same path with the heat/sun blazing, and the AC roaring.

When we get into the fall and down into the 60's... you're gonna see some serious high MPG screenshots. I hope you'll be able to handle it...

 

Intentional? Absolutely positively Yes. To deceive you? Not really, but more to keep drivers challenging speeding tickets from claiming that their speedometer displayed a legal speed.

Numerous jurisdictions around the world require speedometers (from the factory) to not read lower than true speed. In the old days of analog speedometers, which often had significant errors, this required manufacturers to bias the speedometer to read a bit high, so that few or none of the devices with errors on the low side would read illegally low. This was standard industry practice, not just a single car maker. The built-in bias in European markets was typically higher than in North American markets. Numerous old posts here even point to a UN document standardizing the error range of speedometers, though this was aimed at European markets. Some Asian countries signed on. No North American countries signed on, preferring to use some SAE standards instead. The best manufacturing practice was to set speedometers to meet both standards, which partially but don't completely overlap.

With today's digital measurements, the error band is much lower, but traditional market practices persist, albeit typically with less added high-bias today than in the old days. In some models, even small enough for drivers to not detect it without more careful measurements, but the Prius bias offset remains readily visible.

Tire wear, and differences in revs-per-mile between different models, throw in some error too.

 

There is a confounding factor to all of this. The Prius has a bladder gas tank (similar to the RAV4) and these can be wildly inaccurate. For example in my 2021 HyRav on one tank that was reading "empty" I needed 11.5 gallons to fill the tank. On another tank that was also reading "empty" I needed 14.7 gallons to fill the tank. Note that the tank is 14.5 gallons capacity. In both instances the HyRav got around 39 mpg calculated. This is a known issue on the RAV4 but I strongly suspect the same is true for the Prius. Your actual tank capacity varies.

 

I thought they stopped using bladders two generations ago?

 

Did they? I wonder why they still use them in the HyRav.

 

The last Prius with a fuel bladder was 2009. It was used in North America only, not the rest of the world.

 

Only the North American gen2 Prius had a tank bladder. It was there to reduce evaporative emissions. Newer tank and emission control designs were able to achieve the same results without the bladder. In cold weather, the bladder got less elastic, so it couldn't be filled to full, but it wasn't to the extent reported in the Rav4.

Your comment is the first I've heard of the Rav4 hybrid having bladder. I don't see why Toyota would need to use one. Their statement regarding the tank issue was that it a combination of the tank's shape and the fuel sender unit when on an incline. From some reports, it sounded like hitting the right conditions triggered the low fuel warning when there was still about 2 gallons to go before it should..

 

It's a HUGE problem in the HyRav. Lots and lots of complaints about the gas tank. You really have no way of knowing how much gas is actually in the tank when you fill it. The 14.7 gallon fill up was insane, especially considering that I filled it as soon as the light came on. So there must have been some gas already in the tank. The 11.5 gallon fill up was just weird. Same thing, filled it when the light came on. The calculated mileage was vastly different in both instances than the computed mileage on the display. I actually took it to the dealer but they were like "well they can be like that"

 

Yes, but I don’t think it has a bladder. Something else, filler neck or whatever. Toyota did acknowledge a problem IIRC.

 

So you're saying they screwed up the gas tank twice. Figures. I've never noticed the issue in my Prime but then I only fill it a few times a year so I'm not likely to even remember the last fill up.

 

If you had the gen4 Prius screw up, you'd remember it.
On early cars, it was easy to accidentally hit the filler flap shut tab while getting gas. When that happened a another flap in the filler neck closed. Then after about 2 gallons going in, the rest came out the the filler hole.

 

Whoa. That would be infuriating lol.

Reminds of of the time I ran out of gas 10 years ago. I filled a small gas can, brought it back to the car, began refilling and all the gas came flying back up at me and down the side of the car. There was a "special" release button that needed to be pressed in the trunk to allow for what I was doing. Madness!

 

deleted - I think my post was correct, but I'm not 100% and I don't want to take the chance of adding misinformation.

 

We have plenty enough of that around here as it is...

 

Okay, getting back to the original question posed in this thread; just filled up for the first time. DTE said 522.

 

Wow!

 

While I can't speak to the Prius yet (I'm waiting for my Prime), my RAV4 Hybrid does the same thing: displays about 2 mph higher than what the GPS or Waze are showing. And Toyota is not the only one: I had a Honda that did the same. No joking or sarcasm involved.

 

The law calls for a certain level of accuracy from speedometers and odometers. The specifics depend by market, but automakers usually have the speedometer to read high within that range. Drivers have tried to use the speedometer was reading low and blame the manufacturer for speeding in the past.

 

491 HV Range + 30 EV range = 521 DTE