Signed up for an Advanced Driving School organized by the local BMW chapter. First time I'm attending this sort of courses. Two-day course, and even tax deductible (for Canada anyways). Can't wait till May!
Apparently, all the previous students loved it. And many have attended multiple times and commented that each time they learn something new. And the great thing is that, as least for convertible owners, we can still use our Z4 on the course. If bringing in non-BMW convertible, they will require additional inspections before they can decide whether it is allowed. I suppose for the participants' safety sake, convertibles with only OEM roll over protection are starting to get excluded from various amatuer motorsports or even performance driving course. As far as I know, I think the local Solo 1 / Solo Sprint events already required additional roll over protection for open top vehicles. Solo 2 / auto-cross still allows open top vehicles with OEM protection.