Monthly fuel costs in Singapore vary widely based on vehicle type, driving habits, and fuel prices. For a small car averaging 1,000 km monthly at around 15 km/l, costs might range from SGD $120 to $160. A mid-sized car (10 km/l) could be around SGD $180 to $240, while larger vehicles (8 km/l) might be SGD $225 to $300. These are rough estimates subject to fuel price changes.