Can't say I'm surprised that you were able to get by without a front plate. A couple of decades ago I went without a front plate on my X1/9 for a few years before being pulled over. Frankly, I think he stopped me more because he wanted to get a better look at the car and less because he was concerned about the lack of a front plate. In any case, my town is small enough and red sports cars are eye catching enough that the officer would probably have noticed if I had "forgotten" to display the plate after being warned. After that incident I had front plates on all my cars, until last week that is...
