Significant Difference in Data Logger Speed and Speed Displayed

[spsajewski]

I was testing top speeds around Route-X with the hope of using the data logger to create reliable top speeds to the nearest mph for my 300 mph Club thread. Unfortunately on the three runs I tried, in three different cars, I noticed that the data logger was registering speeds ~4-8 mph slower than the speeds shown during the run. Has anyone else found this same issue and if so, have you found any way to calculate an accurate speed?

 

[ryzno]

I didnt notice the top speed being off, but the data logger runs in a light slo-mo, with a unadjustable speed. with no time reference, or numerical value for G's. I find it useless for drag racing tuning.

 

[bread82]

There also appears to be a discrepancy between driven wheel speeds and vehicle speed within the data logger. Another member saw wheel speeds 75 mph faster than the vehicle speed!
https://www.gtplanet.net/forum/threads/data-logger-what-uses-have-people-found.306705/

I'd not noticed a difference between cockpit displayed speed and data logger vehicle speed, interesting. 4-8 mph at close to 300 mph.... that's ~1-3%, almost sounds like a rounding error somewhere in the code which got carried through. Kind of like the torque values in the settings menu and garage view differing by a bit.