That's right, the Unites States of America, the "Greatest country on Earth" has not adopted the metric system, just like Burma and Liberia.
I'm not entirely sure what your point is. Yes, the United States moronically continues to use a silly, outdated system of units and measurements (among others since, as was mentioned, Brits still partially use Imperial units as well). So
Gran Turismo should be 100% in metric to "punish" those of us who use Imperial units in our day-to-day lives? Or perhaps you're intending to imply that the lack of Imperial units in
Gran Turismo will be the tipping point that will push America into adopting the metric system?
The point is, I'm not arguing the merits of Imperial units. It's just the reality of the situation that we Americans use horsepower as a measurement of engine power, miles for distance, and pounds for weight. The first two of those are available in GT6, so it seems logical to have the latter one as well. (Additionally, car measurements could also stand to be in Imperial units, though I don't
think car enthusiasts pay quite as much attention to the length, width, etc. of cars as they do to weight, so it seems like a lesser priority.)