There are a number of different terms that can be used to refer to a vehicle's petrol gauge. One common synonym is fuel gauge, which is a broader term that can refer to any type of gauge used to measure the amount of fuel in a tank. Another option is gas gauge, which is more commonly used in North America. Other potential synonyms include petrol meter, fuel level indicator, and fuel tank gauge. No matter which term you use, however, the function of this important instrument remains the same: to help drivers keep track of how much petrol they have left in their vehicle so that they can avoid running out while on the road.