Braking. Motorweek test result was 60 to 0 in 115 feet which in doing the math works out to 1.05 g. Car & Driver did 70 to 0 in 189 feet which is equal to 0.87 g. Assuming there was nothing wrong with the brakes on the C&D test car, the difference might be explained by:

Road surface friction difference and tires (Turanza vs Potenza).

Could those differences amount to that much increase (20%) in braking distance? (If the C&D testers had equaled the rate of deceleration achieved by the Motorweek people, their distance would have been 157 feet.)

I think so! If HPT gives better performance I would hope that the braking distance difference would be at least 15 feet from 70. That isn't even one car length. And another 15 feet or so because of a more "slippery" test surface? Possible, of course.

Sounds better to me than that the brakes weren't up to par (a possiblity now that I think of it...glazed pads or whatever, although they say "at impending lock-up") or that C&D testers don't know what they are doing.