There is no racing game with better netcode than LFS... with 56k you can play with up to 6 players or something... in Need for Speed (bah) you have lag still when everyone has 100Mbit...
The main 56k problem is packet loss, which cant be incluenced by any code, it' just like that.
Also, by far most racers are from europe (like 50%), and only 13% from the USA. Thus most servers will be located in europe, and your ping will not be nice then. the usual 300ms + another few hundreds...
So you have baisically a ping of half a second.
But I guess you are right aswell.. in a way.
There is nore data that needs to be sent (I guess at least), because of the new damage / telemetry features etc.