GPS MPH vs Dash MPH

Yup, I noticed that too. If I set my cruise control to 36 MPH the radar equipped sign a block from where I live will show 35 MPH.

 

Yep, My Prime is like that and so was my Gen 3 Prius. I always thought it was my 17" tires on the Gen 3, but I guess not now...

 

mph display is off by legislation: they don't want people going faster than posted speed limits. I guess that went out the window...

mpg display is off due to Toyota compulsion to BS, and not connected to above.

 

All of the EU, for one. I've heard that certain lower level US jurisdictions have similar laws. Regardless, this is essentially industry standard practice.

The odometers do not have the same error, in fact class action product liability lawsuits over warranty fraud have pushed some makers to make their odometers intentionally under-read by 1-2%.

The internal computers know the true speed more accurately. You can see this with a ScanGauge-II or any other OBDII engine monitor. It is the speedometer display that is intentionally fudged to read slightly high in North America, significantly higher in the EU.

... but at least that takes away a driver excuse.

 

Here's some really dry reading, I couldn't hack it.

Speedometer - Wikipedia

 

If it really bothers you, upsizing the tires is a simple way to "correct". A 205/65/15 tire would fit nicely on your rims, it is 2% larger so actual MPH would be 2% faster than currently reported with your stock tires. You will also see the reported distance and MPG drop by 2% for the same trip.

I actually did this with my 2004 prius...Ran with 195/65/15 tires vs. the stock 185/65/15 and felt everything (MPG, MPH, etc.) was more accurate. 2% is a pretty small number but if it makes you feel better, it is an option.

 

Doing this to correct the speedometer display will result in the odometer now being off. Which could be construed as fraud.

 

It does seem tail wagging the dog.

Funny, "solutions" of this sort come up so often, I've just given up commenting.

 

there was another member here who was going to start a class action lawsuit because the odometer was reaching warranty before the car. i wonder how that is coming along.

 

Manufacturing done this on a purpose, they want to make you think you are driving faster than what you actually is. BMW, Mercedes they have the range of 5-15 mph faster than the actual mph.

 

How can this become a lawsuit? Lol...

 

A couple of such lawsuits have already won against the manufacturer.
bisco's wording could be a little confusing. The complaint was that the odometers were reading faster, cutting the cars off from warranty coverage before they had truly hit the mileage limit.

 

My 16 and now 17 came with 195/65-15 tires 25" outside circumfrence which gives the correct odometer reading, Toyota was undersizing the 15" wheels and is still undersizing the 17" wheels.

My wife's BMW X1 was the base model and the wheels were undersized, so without a gps you were always holding up traffic

 

funny thing is, some government agency doesn't want you speeding, but the cops could care less.

 

Just editorial: I think you mean couldn't care less?

 

On bmw you can code it so that it shows the correct speed