Speedometer

The raw data on the OBD-II bus is correct, but the speedometer readout is programed to read high. Or so I have heard.

 

My odometer is off by same ratio as speedo 3%

 

How are you measuring it? Are you still using the OEM tires?

Over a 90 mile stretch of I-90 in Washington State, starting just past a known 'bust' between mileposts 218 and 219 (just 0.4 mile apart), my odometer differs from the mileposts by between 0.1 and 0.2 miles.

 

So your warranty is for 3% fewer miles than stated. You might wish to notify TMC about that, and get a written extension of your warranty.

 

It should be a no-brainer with today's technology to have accurate speedometers. The inaccuracy leads one to speculate on a possible motive.

 

This morning, I checked 20MPH on my 2014 PiP --> 18MPH on Scangauge.

 

Watch this video. There are more factors at play than are apparent. The ODB-II data gets rather funky on some changes during slower speeds.

I didn't realize the effort Toyota made to smooth out the readings. Being a little high at times sure beats it being way off like that.

 

3000 miles for every 100k?
Why not?

 

Why not what?

 

Why not try to get extra warranty?

 

I have driven many rental Prii in the US and my own Prius PiH in Europe and I noticed that the speedometer reading for the European Prius appears to be significantly more "optimistic" than for US models:

A Swiss review of the PiH highlights this wide difference:

90 km/h (effective) at 100 km/h (indicated) [=-10%]
113 km/h (effective) at 130 km/h (indicated) [=-13%]

whereas in the US, it is always within 2 mph of reality.

On the other hand, I found that the odometer readings (and fuel consumption stats!) were remarkably super accurate. So this excludes the 15" vs. 17" wheel size being a significant factor.

I think Toyota deliberately programmed the speedometer in this way, not so much to "protect" their drivers from speeding tickets (we are talking about Prius drivers after all ) but to encourage us to drive slower, at more fuel-efficient speeds. This will be significant at motorway/freeway speeds (since fuel consumption will be much influenced by wind resistance that is proportional to the square of the speed - e.g. twice as much aerodynamic drag at 75mph than at 50mph.)

 

That, and federal law requires speedometers to have an optimistic bias.

 

I lease and will easily be under my milage allowance, so I don't care!

 

But that means your mileage limit under the lease is effectively smaller than it would be with an accurate ODO.