Trip Display Overstates MPG

You ALWAYS fill up to the top of the filler neck? The calculated always matches the MID diplayed mpg? Hmm Interesting.

 

I think it may be that the speedometer (and odometer) are wrong. Township put up a bunch of those radar controlled "Your speed is: XX" gizmos around town and the Prius is consistently 2-3 mph less than the radar is reading. 50 mph on the Prius is 48 mph according to the sheriff.

I'm guessing the radars are calibrated as they were just put up and there must be a campaign going on and the lower speed is consistent with three of them I saw today.

 

The Prius has a known 2mph too fast error on the speedometer. This has been verified with GPS and Scagauge. The car's computer knows the real speed, however.

The Odometer has checked accurate by those who have taken the time to do so.

 

The spedometer shows your speed about 2% high I believe due to legislation: the logic being that if it tells you you're going a bit faster than you actually are, it'll reduce the severity and/or occurance of accidents, and improve your fuel consumption.

The "optimistic" mileage reporting is a separate issue. Motive is a big factor: now who would benefit from this?

I've been tracking our mileage for about 18 months. The error varies between about 6 and 8 percent, with the cumulative error to date at 6.9%.

 

Toyota must be spending a lot per car to get two different sending units reading speed and miles since both are read via the tire rotation and then calibrating them different and having cars computer read and display them differently.

Someone mentioned legislation requiring speedometers to display low but I don't see any such laws. Since a lot is made of odometer readings for legal issues, tampering with them to create false readings is definitely against the law.

I guess there is some range of accuracy that the car manufactures must meet but to go all the work required to read and display two different miles per hour calculations seems extreme and for no business return to Toyota.

 

Nope. Single sender. The speed display shown to the driver is simply programmed to read high.

This has been beaten to death in many prior threads. Everyone does it, not just Toyota.