'some' MK3s do not respond... likewise, some mk2s.... oh and mk1s do not respond
i wave... i tend not to respond... why? cos i am the one waiting to be responded to...!
Oh but..... not unusual but a couple of years ago a chap in a red TR5 (or 4a) waved to me first.
I was quite overwhelmed and honoured
My humble (but luvverly)5 and his gorgeous classic 5
I often wave to any other convertible that may have its roof down (proper convertibles I mean - not these modern 4 seater coupe convertible things ) and get as many waves back, in percentage terms, as I do from other MX5s