[jdean]

Square tubing is indeed much stronger supporting vertical loads than round tubing where the round tubing is of equal diameter to the height of the square tubing. For loads that are changing across the diagonal of the tubing, in other words coming from multiple directions, the round tubing is marginally stronger than the rectangular tubing.

Most frames, whether round or square, have a lot of horizontal cross bracing running parallel with the main chassis rails which help support non-vertical loads. So I think because of this the square frame, pound for pound, should be stronger. BUT I agree the round style is more "Correct", and either tubing can be built plenty strong for these cars. FFRs round tube design looks very well engineered to me, and is their best feature IMHO.