Summary of problems reported on Prius 2010

[tumbleweed]

Originally Posted by PrincessPri

During the past week, I've gone past several of those machines that digitally tell you how fast you're travelling. I've driven past 5 of them this week and I noticed that the MPH on the car is 2 MPH greater than what was being tracked by the machine. (I was the only car in range that the device was reading).

I don't know if the car is incorrect or all 5 of those tracking machines are incorrect.

Maybe Toyota is looking to slow down the leadfoots by making them think they're going faster than they actually are.

Thanks to Ken1784 we know why the speedometer is either right on or fast. It's due to a U.N. regulation:
http://www.unece.org/trans/main/wp29...gs/r039r1e.pdf

Check this thread posts 25, 26, and 27:
2010 Toyota Prius FCD Inaccuracy

[blisspacket]

Here are two more items: Brakes: traveling at creep speed I've twice experienced touching the brake LOCKS the brake. Nothing modulated about the response of the car. It's as if you'd pushed the park button.

Also brakes associated: Red light ahead, off on the gas and very light brake, and the display properly shows energy flowing into the battery. Then after stopping, or at creep speed, energy flows battery to motor. Light brake pedal brings the car to a full stop but display shows energy continuing to flow to the motor. FIRM brake pedal turns that energy flow off--but there's nothing finessed about that firm brake. I think that setting is at way too crude a level for this sophisticated machine.

[OZ132]

Originally Posted by skyking

Same observation using my Mio GPS car showing 2 mph higher than actual. My Gen 1 was spot on at all speeds.

Could this be related to incorrect MPG readings?
If Speedo reads high, does Odometer read high, also? If Odometer reads high, would MPG read high?
Or, not?

[1 mad scientist]

Tumbleweed,
Both my 2008 Sienna and the 2010 Prius show up 2 mph slow on these radar devices. It is very consistent. I did a quick check. Look for the mile markers on the side of the highway. Set the cruise to 60 mph. Pick a mile marker and time how many seconds it takes to reach the next marker. At 60 mph it should tame 60 seconds to go 1 mile. I found both vehicles are very close to 60 seconds. I believe the radar units have some kind of offset for the display that reads 2 mph lower than the measured speed.
Bob

[Goleta]

Originally Posted by blisspacket

Here are two more items: Brakes: traveling at creep speed I've twice experienced touching the brake LOCKS the brake. Nothing modulated about the response of the car. It's as if you'd pushed the park button.

Also brakes associated: Red light ahead, off on the gas and very light brake, and the display properly shows energy flowing into the battery. Then after stopping, or at creep speed, energy flows battery to motor. Light brake pedal brings the car to a full stop but display shows energy continuing to flow to the motor. FIRM brake pedal turns that energy flow off--but there's nothing finessed about that firm brake. I think that setting is at way too crude a level for this sophisticated machine.

We have also experienced the problem of the brakes abruptly grabbing, which is discussed by us and others in a thread on PriusChat ("Braking in Reverse").

[CivicQc]

Originally Posted by blisspacket

Also brakes associated: Red light ahead, off on the gas and very light brake, and the display properly shows energy flowing into the battery. Then after stopping, or at creep speed, energy flows battery to motor. Light brake pedal brings the car to a full stop but display shows energy continuing to flow to the motor. FIRM brake pedal turns that energy flow off--but there's nothing finessed about that firm brake. I think that setting is at way too crude a level for this sophisticated machine.

Blisspacket,

thanks for the info. If you can find (or start) a thread that describes the problem, and that shows that other people have experienced it too, etc. (see the rules in post #2), post the information on this thread then I will add it to the list.

[Jon S]

the auto-dimming mirror does NOT work as designed....

:P

[Jon S]

Originally Posted by PrincessPri

During the past week, I've gone past several of those machines that digitally tell you how fast you're travelling. I've driven past 5 of them this week and I noticed that the MPH on the car is 2 MPH greater than what was being tracked by the machine. (I was the only car in range that the device was reading).

This is by design and is true of almost all cars... New tires have a larger circumference which will overestimate the actual speed. As the tires wear down, the smaller circumference will give a more accurate speed.

[hampdenwireless]

Originally Posted by Jon S

This is by design and is true of almost all cars... New tires have a larger circumference which will overestimate the actual speed. As the tires wear down, the smaller circumference will give a more accurate speed.

That is not enough to account for the speed differences that are seen.

Almost all speedometers will read fast on almost all cars. Manufacturers can legally make the numbers appear higher (IE the car is going faster then the speedo says) but if they do the opposite then they are breaking laws and even UN regulations.

Most cars are 2-5mph high depending on speed.

Also if your speedo read low you could (try to) sue your car company for getting a ticket, while the opposite is legally allowed (you cannot sue your car company for wasting your time!).

So this is not a Prius problem.

[dhs]

Originally Posted by hampdenwireless

That is not enough to account for the speed differences that are seen.

Almost all speedometers will read fast on almost all cars. Manufacturers can legally make the numbers appear higher (IE the car is going faster then the speedo says) but if they do the opposite then they are breaking laws and even UN regulations.

UN can make recommendations, but in the US, at least, nothing the UN does is legally binding.