I got pulled over in my Viper about 2 years ago for speeding. 72 in a 60mph. I had just been going much faster than that around a curve so I felt relieved if you could believe it.
After careful inspection the officer who was actually quite polite noticed the front license plate was not there. He told me I needed to have it there per state law. Didn't make a big deal out it.
I drove my daughters BMW 328 which is white with a black trim on the bumper with no license plate. I had just gotten the car from an out of state owner and had not gotten the hardware yet. With that color combination, no license plate is pretty obvious.
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The Viper without a front license plate is not near as obvious.