Cruise control speedometer vs Google maps speedometer don’t match so which is correct?

[Atlantis Blue Emira]

Anyone encounter this when they are on cruise control? (I have only used it twice as I like to drive the manual, but was cruising in touring trying to get my mpg to 20 mpg and failed )

The dash speedometer shows one speed while google maps shows usually 2 to 4 mph less.

Depends on speed

Observation: is if you’re over 70 miles an hour it’s 3 mph off (Google maps speedometer slower) and if you’re over 80 mph it’s 4 mph off. I have stock tires and rims so I know it has nothing to do with the configuration but with modifications, I know it can affect the speed of the dash, if not calibrated to the tires.

 

[DriverMod]

I’ve noticed the speedometer is very optimistic as well. I have measured the same discrepancy as yourself.
I guess it gets me past the 1000mi break in more quickly though…

 

[KAR120C]

Anyone encounter this when they are on cruise control? (I have only used it twice as I like to drive the manual, but was cruising in touring trying to get my mpg to 20 mpg and failed )

The dash speedometer shows one speed while google maps shows usually 2 to 4 mph less.

Depends on speed

Observation: is if you’re over 70 miles an hour it’s 3 mph off (Google maps speedometer slower) and if you’re over 80 mph it’s 4 mph off. I have stock tires and rims so I know it has nothing to do with the configuration but with modifications, I know it can affect the speed of the dash, if not calibrated to the tires.

This is totally normal and is common on most cars. Speedo error is allowable as long as it overstates speed and not understates.

My Emira speedo is 2 mph higher than GPS AT 80 mph.

 

[Aero]

Same % off as OP on mine. All our European cars are off similar %. Some rule that they can show a bit fast originally but not indicate slow at all if the owner decides to change the tire size a bit.

 

[Eagle7]

This is totally normal and is common on most cars. Speedo error is allowable as long as it overstates speed and not understates.

My Emira speedo is 2 mph higher than GPS AT 80 mph.

Same. Wayz and my VAIO dash cam both show me at 2 mph slower than the dash speedo. We have those speed limit signs here that show the speed limit, and underneath is a speed scanner that shows your actual speed. It also shows me at 2 mph less than my dash speedo.

 

[Anothernimbus]

Same here, speedo is always 1,2,3 mph higher than scanner or Google maps gps speed. Depends on how fast I am going. We have a lot of 35mph scanners here and if speedo shows 35, the scanner is usually 33mph. My other cars are spot on.

 

[CoryC]

I'm consistent with everyone else... 2-4 MPH higher, depending on how fast I'm going. I'm a waze user...