Speedometer weirdness?

What is weird is your temperature gauge! Mine read 88 degrees yesterday.

I thought those red speed limit signs were the only color they had. If I go under 50 in a 45mph zone someone always honks at me as they take off my tail doing 55 or more.

 

Have noticed the same thing, displayed MPH is frequently one less than the cruise control target, even on open road when no one is around. Same model/trim.

 

Ditto. I've taken to automatically setting my cruise 1mph higher. It seems to be a "safety" feature so that the car has a little leeway with the speed but never exceeds the set speed. I've noticed it will reach the set speed after clearing a hill or during a downhill coast.

 

i doubt it's intentional since our 24 hycam shows the same speed

 

1mph difference in the display can be just 0.1mph difference.

 

I am experiencing the same thing when I use DRCC in my 2023 Prime SE, many times the car maintains a speed of 1mph under what I set.

 

Not anywhere near micro-watt or nano-watt. Not even pico-watt.

How does sub-femto-watt sound?

"The GPS receiver receives GPS signals at 1575.42 MHz (L1 frequency) at a power level of
-125 dBm (about 0.1 fWatt)."

A couple other sources mention -130 dBm.

 

It is the same thing in Gen 4 with TSS 2.0. Cruise control controls the speed within ±1 mph, not ±0.1 mph. It is more often −1 mph than +1 mph.

Moreover, on my Gen 4, the speedometer intentionally displays 2 mph higher than the actual speed at all speeds. You can check it with the Google Maps navigation.

As for the red road sign, that is strange. Could it be because you set the cruise control above the speed limit? That would be my guess.

 

Speedometer wil always read 1-2% high on any vehicle. Manufacturers (Lawyers) don't want to be liable for speeding tickets. See Section 5.3 of the attached.

 

Same reference source doesn't mean they have to use the same display rules, such as how to round the decimal, which the computer knows.

Most likely, it is the legal reason that has been pointed out. There are regulations dictating the accuracy of the speedometer, with CYA leading the manufacturer to having it read on the higher than actual. The cruise setting isn't has constrained.

Between the sensor and the road is a soft material that wears with miles, and the inflation of which changes with temperature. All of which leads to changes in the distance traveled from each revolution of the sensor.

 

I'm pretty sure it's the rounding. I think the red is triggered by anything at all over the speed limit. So if the speed limit is 50mph, then 50.0001mpg triggers a red sign even though the speedometer will continue to read 50 until the actual speed reaches 50.5 or 50.5001.

Different teams working on different functions over many years.

 

A 'your current speed' sign in my town is like that. Does the flashing while displaying the legal speed. Trains you to just ignore it in my experience.

 

I've found (on our gen 3), regardless of plus/minus vagaries in speed on cruise, say 1~2 kmh to either side, if I set it to a speed, it'll settle back to that speed, not one under. Could be something a software update would fix?

 

The systems could be working in kilometers, and the displays are rounding the miles conversion slightly different.

 

Yes, that is exactly what I meant by "intentional."

However, in the case of Prius's digital speedometer, it is not a percentage. As I asid, it is +2 mph regardless of speed. So, if you are at low speeds, it is a lot more than 2%. My 1985 Corolla's "intentional" calibration for its analog speedometer had a much higher difference from the actual speed, and it was more like a percentage.

 

My gen3 Prius v display is more like 3% high compared to its own real speed accessible via obd2. At low speeds the difference is small as you would expect with a percent factor.

In fact I monitor real speed and coolant temp in realtime and have for years.


This P10 device also has configurable alarms.

 

I see. It is a constant difference of +2 mph in my Gen 4.

In your case, there could also be a problem with your tires' "revolutions per mile" spec; so, it may not be an intentional-calibration issue—rather an unintentional one. I am surprised that my Gen 4 is so accurate at all speeds other than the constant 2-mph intentional addition.