More realistic is a mechanism that controls the speed of the cars whilst not penalizing drivers who have built up leads etc. How about an FIA-controlled speed limiter that engages after a 5 second warning period (so that the driver does have time to prepare for the loss of performance)? Cars remain, more or less, with the same gaps and their ability to have an incident at lower speed is reduced for the duration of whatever the incident is. The switching off of the limiter would also have the same 5 second warning period so that the drivers could, again, prepare for the change in performance. Boom, no fundamental car redesign, just a software update. This solution to be known as MezCon (TM) from now on.