In many countries a car without a functional speedometer is not allowed on the road, for safety reasons.
Besides, GPS can only update once a second. And given the signal jitter you can't get a good speed reading from the last two fixes - when you are going in a straight line. When you are not going straight, the GPS based estimate must underestimate the distance you travelled and thus your speed.
Using this toy speedometer thingy for driving is just dangerous and insane and illegal in so many ways that I wish the article could just be pulled from the web.
this is well known in the prius chat boards.
Toyota also knew about it, but instead of making it a safety recall, they put out a service bulletin: T-SB-0172-09 Combination Meter - Intermittent Display
If you search the web for that you will find a ton of hits.
The solution is to replace the entire instrument cluster circuit board. If you have a replacement board, It's relatively easy, maybe an hour of work if you are handy, and there is no soldering unless you have no replacement and want to replace the bad capacitor yourself, and maybe a transistor. You will probably break your A/C vents in the process because they are made of a type of plastic that becomes extremely brittle with age.
There is a guy in Texas, Texas Hybrid Batteries, who will sell you a refurbished dash circuit board for $150 if you mail him yours. Buying a new one is a bit spendy and may require going through a dealer depending on laws, since the odometer is part of the assembly and has to be 'flashed' to what your vehicle was before the swap. However on cars of this age the odometer is often up to about 200,000 miles and exempt from a lot of the odometer laws.
Drivers who want to go fast will go fast - for them the gauge is only useful so they can slow down for speed traps.
Not having a speedometer shouldn't make a sensible driver suddenly very dangerous at all.
of course. Any sensible driver will not drive the car without a speedometer.
I think you missed the point of my comment entirely.
Knowing your speed is not required to be safe while driving - being observant, correctly signaling, and driving at a speed appropriate for the conditions are.
Yes, they really do. Just ignoring the fact that people tend to drive faster when they don't have a speedometer, people already travel too fast for road conditions as a matter of course. Let alone the fact that at residential road speeds, the difference in life expectancy of someone hit by a vehicle drastically changes with even a slight increase in speed.
Safety checks exist because vehicles are roving machines of death driven by easily distracted people, who have a long track history of ignoring what they can't see.
Your life shouldn't be put in danger because some other arsehole decided that it's perfectly fine to drive a rust bucket with nothing more than a sheet of paper left by way of brakes, or with lights that are so badly adjusted anyone else gets blinded, or with windows in a state that someone sneezing will shatter them, or any other number of things.
But yeah, authoritarian government overreach. Sure.