Ill bet they put the speed limit on just to stop the Cadillacs being embarrased, and to give the Yugos a chance at getting nearly to top speed.
Plus, it would have had a lot to do with insurance and the fact that they couldnt enforce restrictor plates under the carbies.
Plus, you can blame the driver of the Thunderbird for causing the lower limit.
Bruce,
The Tassie Devil(le),
60 CDV