How accurate is your speedo?

I recently purchased a GoPoint OBDII along with the Dash Command app for a iPAD. I installed it into my 360 to see how everything was working, speed, temps etc.
Well after using it for a little while I noticed that the speedo was off. It seemed to get progressively worse the faster I went. My 45 was reading 40, 80 was 70. I'm pretty sure that my speedo was off because when I came upon a police speed sensor (on the side of the road) it said I was doing 37 when I was doing 40. So, I'm a bit curious is the speedo connected to a cable or is it an electrical connection through a ECU?

 

My 360 speedo reads ~5+ mph faster than my GPS at 60mph...even more of a discrepancy as speeds increase.

 

Yep... Speedo is not even close, common issue. Not sure how it works...

 

Mine reads around 5 mph higher than actual at about 75 mph.

 

I've been told by a mechanic, they are all like that. Altering your tire size will also effect a bit.

 

Mine is optimistic as well. Reads 81mph at 75mph by GPS.

 

Mine is very optimistic. Reads at least 5mph higher at 70+ mph. I have the OE sized tires and wheels too. I've chalked it up to being normal after hearing everyone else has the same.

 

Mine is off by about 9%

 

Depending on which wheels I have mounted my 430 reads high by 5-8%.
I had the same experience with my 360.

 

Last time I checked I thought mine was pretty close but I was using Trapster for my mph.

 

I'm off by about 5 MPH too, 02 360 spider.

 

When I'm on the highway, and the speedo is reading about 79, my in-dash GPS display says I'm more like 70-71. I have found that my speedo isn't terribly accurate, but I don't really care...

 

Same as everyone as above. My wife's BMW has the same issue. The GPS and the cars never agree. Mechanic tell me the same, they are all like that.

On a positive note you can tell everyone you were doing 80mph the whole and cops wouldn't even try to pull you over. Ego booster!!

Deiger

 

Mine too

Not a bad thing though...lets chance of getting a speeding fine

 

Ok checked today, at 70 mph on my gauge the GPS said 68 and at a century on gauge it the GPS said 96. I can live with this. I used Trapster for my GPS reading FYI.

 

My experience exactly for both models

 

My 360 speedo reads high as well. At highway speeds, seems to be about 5mph high. Have not compared it to GPS.

 

After almost 30 years and who knows how many Fcars..... they ALL have had optimistic speedos. Maybe Ferrari just want us to not get tickets!

 

Mine was 5 to 8 mph over, but the real question is, does this effect the odometer?

Do our Ferrari's have fewer miles than indicated?

Idk, maybe one of the experts will chime in

MB

 

Ferrari does it to make us all feel like we are going really fast

 

my speedo is off about 10%, but mileage indicator is right on, so mileage is right, speed off a bit

 

Normal for all cars, this is a common complaint on any performance car forum for any make. At least the 360 speedometer doesn't start vibrating and bouncing up and down for any reading over 100 like many cars do.

 

At least that is what we want to believe. in reality they probobly just didn't care enough to make it accurate, or didn't even notice it was an issue. If it were the other way around, I imagine a safety recall would have been issued, as people driving 10% faster than the speedo indicates could become a safety concern.

 

You're really lucky Kevin. My 575M Maranello is more than 10% optimistic. I've measured it not by GPS but by the clock at 10 mile mileage markers on Interstate 87; at a steady indicated 80mph my actual road speed was bet 71-72mph. The odometer had a similar deflection.

 

Try the Trapster app! Maybe you will be closer.... ;-) LOL