The way I did it, specifically, was to get a datalog using my SCT X4 at the track. I then imported the log and read the columns for Time and Vehicle Speed, in Excel. This gave me 4.808 to 4.835 seconds, depending on run.
Bruce, if I use the calculator you linked, it gives me a 0-60 in an estimated 4.37 to 4.44 seconds.
That seems like a non-negligible difference. I'd love for the quicker one to be more accurate, but my gut always tells me the slower number is usually the accurate one when it comes to these things, lol.