Hi
With a bit too much time on my hands - and keen to find a reason to get out of the house this week, I tried out a couple of these.
I appreciate they are inherently variable as they rely on a good satellite reception.
I compared 0-60 and 1/4 mile times on a known quantity for my daily car (alfa 159) where specs are readily available and results were close enough (within less than 1s on both measures ) the "Ulysee Speedometer"was the most accurate.
Chuffed with the times for my mini as I was careful not to wring its neck and I kept under 6000rpm ..... - but the real test will be the RWYB in Feb...
If you do try them out..... do please be very careful
Best
Matt - Brighton UK