I must have been asleep when the gas prices went up last because they've just gone up again by about 5% to 4.86 RMB/litre.
That's 0.325 GBP/litre or 2.29 USD/US Gallon.
Taxi drivers, particularly, are up in arms and are talking about giving up in large numbers. They have had a rise in prices recently as 10RMB now gets you 3km, not 4 but I'm not sure how that stacks up against their costs.
In Guangzhou recently we were charged a fuel surcharge of 5 RMB on journeys to the airport (I only noticed because they gave me a bunch of 0.9 RMB fa piao invoices to cover it).