To those who think petrol is cheap in qatar never knew that the cost of diesel for non transport use like power generators and industrial use is 3.50 qr/liter.It is heavily subsidised by government for transport use to help build the nation and keep it running smooth. Same is true for Petrol some of which was until recently imported because the local production wasn't enough to meet the demand.Unsubsidised it would cost around the same as diesel.
Have a look at our neighbour UAE where petrol is retailed at approx 2 qr /liter[again with govt incentives].