"I would say IFMAR typically but several of the places I've been have been really bad about having an "IFMAR" mentality and letting the faster car through"
That seems to be the thing with IFMAR that most people don't get it that it is against the clock not each other. I know when I first started it was hard mentally to just let other by but now that I have been doing it awhile it really makes sense.
We do heads up starts at our track for club races but IFMAR for big races and some of the people that just do the club races mainly don't get it right away. We have been using the transponders during club races to get the newer people used to it and how it works for big races.