The vast majority of Singaporean taxis run on regular gasoline and not CNG. CNG was introduced to a portion of the Singaporean cab fleet within the past five years. The driver mentioned that the slightly slower acceleration of a CNG vehicle compared to a gasoline vehicle didn't bother him much. Cruising on highways he observes no discernible performance difference. He said that during the oil price increase in 2008, the cost of CNG was lower than that of gasoline, but that now that oil is $50 per barrel he doesn't think there is much of fuel cost difference.
Oil 101 outlines why CNG is suitable for city taxi and mass transit fleets but is not practical to use as a fuel outside of urban areas. The Singaporean experience shows that CNG service station roll outs can be a challenge even for ultra-well managed urban areas.
Vietnam: I am in the scooter capital of the world today: Ho Chi Minh City (Saigon), Vietnam. Cars are second class vehicles here and I don't see many push bicycles (which is a big change from 10 years ago). I ride a scooter and motorcycle in New York and am familiar with the benefits and hurdles such vehicles face in a city. Scooter owners in Vietnam drive aggressively. You can tell they are used to ruling the road over cars. There is a lot of scooter-pooling. By my estimation over half of the scooters here carry two passengers. It is the rainy season in Vietnam but that doesn't deter scootering. Drivers and passengers sport a vast assortment of ponchos. Beer delivery even takes place, somewhat precariously, on scooters (see the video below I took earlier today).
Vietnam is a still a net oil exporter with very low but rapidly growing per capita oil consumption (approx. 1.5 barrels per person per year compared with around 24 in the US). There is no sense of anyone in Vietnam cutting back on oil consumption as a result of high oil prices and from the level of economic activity here (5%+ yr/yr growth is generally expected in 2009) one doesn't feel we are in the midst of a global recession.
(above: video I took in Ho Chi Minh City, Vietnam this morning)