Couple of years ago I got interested in second hand car market in Bulgaria and was not surprised there is not available data for it. I tried to proxy it with the data from a mobile.bg - the largest car sale site in the country - see the post here. Тhe approach had some downsides but still delivered some data. However, it was a partial effort as a proper estimation would require regular data extraction and comparison and I had not had the time to do that. The good news is, thanks to EU Open Data effort, the Bulgarian government has recently published data for registered motor vehicles. Please find it here, in Bulgarian only. It is a good step forward and I welcome that. The data is missing some important details such as mileage and engine type (diesel, petrol, electric) and could have been better organized but it way better than no data at all. I was not happy to confirm some of my conclusions about the age of the car park as it is a sign the economy is not in the country it should be after more than 20 years of free market.
I hope the Open Data initiative will not die and the government will keep publishing data on regular basis to satisfy the data curious minds.