::::2 - closed wheel as opposed to open wheel. I find 'Bodied' to be confusing as body is not defined anywhere. Open-wheel is a reasonably common term, closed wheel is obvious by comparison. But I'm far from settled, I just could not think of a better describer. 
 ::::3 - I use Gran Turismo as it explains what GT stands for. 
 ::::4 - six/eighteen times longer. It is definately relevant is it estblishes in the minds of those perhaps unfamiliar with sports car racing comparisons to motor racing they may have heard of. It helps highight the difference between Le Mans and the much more well-known open wheel style racing. Comparing to Sebring and Nurburgring I would find much less useful to explain to the general public style of reader as these races are much less well known. It's like explaining to a NASCAR fan that Adrian Sutil is a much better driver than Esteban Gutiérrez or Mikhail Aleshin. Without a more familiar frame of reference, the comparison is meaningless.