Those who are only vaguely familiar with Abu Dhabi, may think that the only valuable export is oil. Those people are wrong. Abu Dhabi also has license plates. A few years ago, one collector bought the license plate numbered 1 for $10 million. Recently, someone bought a number 9 for 10 million dirham ($2.7 million).
As this article goes on to explain, people aren't buying the plates to put on their cars. They're buying them to put on other people's cars. "Good" license plates are bought as an investment to be sold at a later date for a profit. There are certain numbers that fetch a higher price like repeating numbers or palindromes. Generally the lower the number the better, but "lucky" numbers tend to be worth more. A week or two ago, I saw a plate with 22222 on it. At the time, I thought it was a neat coincidence. I now chuckle when looking back at my naivety at that more innocent time.
Some rental car shops buy them to put on the cars that they rent out. The cars with better numbers can be rented for higher prices. Emiratis expect to be given the lower numbers when renting a car. It seems that it's a sign of prestige. I suppose when most citizens can afford almost any car, there isn't much left to distinguish yourself. It just goes to show that anything can be collectible.