In UAE they have planned to implement ban on car registeration above 15 year old but even few days back it came in newspapers that they just postponded till further notice.

So I guess in Qatar even if it will ever get implemented it would not be before its implemented in UAE. I believe here in Qatar they did some study to ban more then 10 years old cars but still no decisions came out. You can go and buy any car.

As for car checkups go to salwa road. You will find plenty there.

Good Luck

Peace