Speedometer and Odometer Accuracy

[doltmo]

While on a recent cross-country drive I found myself counting mile markers along Interstate 80 in Wyoming and playing with the Huracan's lap timer to check the accuracy of the speedometer and odometer. Here's what I found.

The speedometer on the Huracan reads about 5% to 6% fast (w/ factory tires and wheels).

If you set the speedometer to 80 MPH, you're really doing only about 75 or 76. I've since independently confirmed this with a Garmin GPS.

To operate the car "reasonably close" to posted speed limits I use the following rule-of-thumb. If the speed limit is 70, set the speedometer to 77. If it's 80, drive at 88. This would produce an actual speed of about 73 or 84 respectively - close enough to blend in with the crowd.

The odometer reads about 2% "long". If you drive 100 actual miles, the odometer records about 102 - not that anyone actually cares about this.

[Hurricane]

Thank you @doltmo for the detailed report, it's useful since shortly i will drive the spyder in Italy


Sent from my 3rd iPhone 6 this year using Tapatalk

[cactus]

I'm skeptical. Did you measure your tire pressures as well? That would factor in.

[Fabspeed_Motorsport]

But what about the mileage depreciation you didn't even get to enjoy?