I don't drive these things, but have flown in the back a few times. I believe they are around 4-5 years old and I think they were bought new at the time. Bangkok Airways have 4 in the fleet. They are an improvement on the old ATRs they also fly, but I take it you didn't sit in the last 2-3 rows right in the back. I had the misfortune of sitting there once and can say that the noise from the engines, particularly during taxi, was almost unbearable. You are sitting right by the engines and the insulation is woefully inadequate.