2018 Prius IV Speedometer Setting

I'm not sure if the difference is 2 MPH, but yes, actual speed is definitely a bit slower than what you see on the speedometer. If I'm trying to go 65, I put the cruise control on 68.

 

Compare it to the speed on the Sat Nav. GPS speed above 20mph is much more accurate. Generally the speedometer speed will be a percentage out, rather than a specific static offset. In every car I've ever driven, it's been 10% high, including my 2017 Prius. So it reads 33 when I'm going 30 and 77 when I'm going 70.

 

I've checked mine with the GPS of my SatNav - my speedo over-reads by about 8%.

 

Don't get caught going under the speed limit?


How about this: if you want to go a certain speed, go by the speedometer. If you're in actuality going a couple of mph slower, where's the harm?

 

Mine reads 103km/hr when the GPS says 100; 83 when GPS says 80; 62 when GPS says 60.

Every car will read like that - my previous FIESTA read 108 when only doing 100.

 

Not always 2 mph, but the speedometer is still designed to read high. The Repair Manual (more info), under Meter/Gauge System: On-Vehicle Inspection, has a table showing the intended error:

Code:

TECHSTREAM INDICATION (MPH)  ACCEPTABLE RANGE (MPH)
            20                      20 to 22
            40                      40 to 42
            60                      61 to 63
            80                      81 to 83
           100                     102 to 104
           120                     122 to 124
           140                     143 to 145
           160                     163 to 165
           180                     184 to 186

“Techstream Indication” is the highest speed measured by any of the wheel speed sensors, observed with the Data List feature of a Toyota Techstream diagnostic system, and “Acceptable Range” is the speedometer display. The table is repeated for km/h, but the numbers are the same.

I’ve explained the relevant regulations in a previous thread.

 

In Canada you can

No rush: woman ticketed for driving too slowly on 401 | CBC News

In your province too. - I thought you knew the law?

Why is slow driving an offence in BC? | BC Driving Lawyers

 

In Ontario Canada, apparently since last October it is.

Cannabis legalization

 

Yes, about 2MPH I noticed at 60MPH. Something sort of interesting that I noticed, On a flat level road (I live in FL), if you set the cruise say at 60MPH (so it shows you moving 60) it shows the average speed recorded by the car at 58 MPH. I have a 2016 with the 15 Toyos.

 

I didn't realise a PRIUS would go at 180 MPH? 180 km/hr would have my licence suspended for many years here - and I think my car would be crushed - or maybe that's the 2nd time.

That's pretty well what my 2 different GPS agrees with - in km/hr:


It can vary a bit with tyres which are worn - or flat.

 

Don't conflate one with the other: over-reporting of mph is by legislation; over-reporting of mpg is just Toyota's ploy to cheer up drivers, gain them extra rosy reports from reviewers, stuff like that.

"Fixing" the speedo, and the hypothesis that mph being off causes the mpg exaggeration, both these topics come along very frequently.

 

Yes, true, ever car over-reports km/hr - by legislation it can't be under - so they err the other way, as if tyres are changed/flat/worn and can make them read slightly different.

But - every car over-reports the l/100km - FORD did it on both mine, KIA did it too. Though, it can be a bit different for every fillup. My fill last time was about 8% optimistic which is typical (5-8%) - but this time, it was 11% back the other way - in other words, I actually got 11% better than the dashboard told me (79UK MPG). Different pump might have cut off at different time.

 

Our previous Honda Civic Hybrid reported liter/100km either spot-on or slightly pessimistic, ie: if calculated was 5, it was display 5.0 or 5.1. Pretty much without fail.

But yeah, apparently an outlier.

Back to the "topic", and I used quotes because I'm somewhere between frustration and puzzlement: I can't understand why there's so much consternation regarding a slight over-reporting by the speedometer.

I suspect it's tied to a generational thing: a couple of my kids that drive have told me, in all seriousness, that the speed limit is the lower threshold you should be driving. Sadly, they may be right, or at least in the majority.

 

Many times here I see people regularly 10 mph over the limit.

 

You would not want to get a ticket in BC for driving too slow...

 

Or for coming to a full stop at a stop sign. Ditto when turning right on a red light. Or observing speed limits through playground and school zones.

 

So many cars must be out of blinker fluid too.
Perhaps it is getting expensive & hard to locate so people ration it by rarely using their turn signals.