Sounds like ******** in all honesty.
Take the Honda Fireblade as an example (I know it's a motorbike but the principal is the same) One of the top mags, PB I think, tested about 10 'Blades back to back straight out of the showroom. All made completely different power figures, I think the variance was +/- almost 20bhp!
And magazine testers who spend their lives doing 0-60 tests can rarely get the same figure twice, and figures vary from car to car too. Sometimes you get a "good one" and sometimes you get a lemon.
Unless the cars are doing 0-60 in 3 seconds instead of 10 seconds I fail to see how any checks done by "them" (the police? the insurer?) demonstrate anything valid at all.