Normally, I don't like to tip but I'll do it on occasion if I feel it's warranted. For example, I took a Bolt from Pattaya to Bankok for 1100. It was a nice car, new, plenty of leg room, the driver was fast and efficient, he had three phones going charting the route and made good time. So I gave him a tip. It was over two hour journey after all. He seemed surprised.