To ensure the safety of all participants, open top vehicles (Cabriolet, TT Roadster, S2000, Miata, Boxster, 65 Mustang, etc) are subject to special ACNA restrictions.  From the ACNA rules:

No convertibles will be allowed to participate at any ACNA driving school that takes place at a "race track"- This includes TT's, Boxster's, BMW's etc. Vehicles with factory roll hoops and / or deployable roll over protection will not be allowed. Targa and T-Top roofs are not considered convertibles and are allowed.

For the above excluded vehicles to be allowed to participate at a "race track” the minimum requirements are;

1. A four point roll cage consisting of a main hoop behind the front seats with two rear braces, which must conform to the "broomstick" rule (there must be at least two (2) inches of clearance between the top of the driver's and passenger's helmet and the imaginary line drawn between the top of the car's front wind screen and the top of the roll bar main hoop.)
2. A four and preferably five point safety harness.  Also remember that we have the "reciprocal" rule: The passenger seat must have an equivalent seatbelt to the driver's seat. This applies to all cars.
3. Arm restraints are recommended but not required at this time.
4. Removable hard tops are not considered structural roofs.
   You are encouraged to point out to potential participants that we are primarily concerned for their safety and that of their passengers, and that for almost every convertible model out there, there is some form of relatively inexpensive, aftermarket roll-protection available."
   Please note that BOTH you and your Instructor MUST fit under the broomstick, with 2" min clearance with your helmets on, or you will not be allowed on the track. (STRICTLY ENFORCED!!!!!)