Yes, I had one for a while. I paid about £40 to import it from a bulk supplier in the USA somewhere, by the time I'd paid postage and import duties (plus the fee the Post Office takes for 'administering' the imposition of the import duries...).
It was good fun for a while, but when I was offered £50 for it, it was an easy thing to let go of.
There is a more sophisticated model that offers more entertaining data output, including output directly to a laptop.
I notice also that the winning bidder in this instance has a very familier ID, so you could always ask him for a go!
Now that I have data-tracking as part of my RaceLogic Traction Control, I can imagine it would only take a few minutes with a laptop and a calulator / spreadsheet to output the same some of calulated figures for horsepower, but using the wheel-revolutions to calculate speed against time/weight, which might form an interesting set of figures for comparison to a G-Tech output.
I had one of these! In fact I still have it, but now don't know where it is.. Don't be put off by the miniscule size (I don't know why but I expected /wanted it to be bigger) and the slightly flimsy build quality, mine worked fine and proved surprisingly consistent. The main problems I had were that it took a while to get it levelled and securely stuck to the screen - mostly down to the cheap (but effective) design. Also the cable to the cig lighter socket was a bit too short, so a couple of times it pinged off the screen at the wrong moment due to the tension in the coiled cable. (But I could always have made an extension cable up..) It also didn't work too well on a motorbike (hardwired to the battery) when the rider had trouble keeping the front wheel on the ground. But all in all, the best purchase I ever made on eBay!
The 'gizmo' as it became known did the rounds in my office and we compiled quite a league table - but not without cost! My Nissan clutch just about survived the experience, but my mate's M3 slipped all the way home.. making it an expensive lunchour exercise!
BMW M3 Saloon (S50) 6.46
BMW Z4 3.0 6.62
BMW Z3 2.8 Auto 7.04
BMW Mini Cooper S Works 7.11
Nissan Sunny Gti 2.0e 7.81
Jaguar XJS 4.0 8.01
BMW 525 saloon m20 e34 8.9
Peugeot 106 Xsi 11.48
Ford Mondeo TD estate 20.94
I hope for your sake you can beat my Mondeo Diesel's time... I'll have to find it and post a time for the Saab.