One thing that makes our cars what they are is the rule about a solid rear axle. Many years ago, the Japanese sold fully-independent suspension 12th cars, and they would run rings round the current design today.
I'm not sure about the T-bar / pivot debate, but wherever they run together the T-bar car is always faster on carpet. Maybe those who do make the pivot car go well (eg, Cleveland and Snowbirds) have some secret that they don't share with us, but for the average Joe, a T-bar car is easier to set-up, and faster.