With high gas prices and an under-performing economy, finding a vehicle with good gas mileage is essential if you are a conscientious consumer looking to save money.Understanding fuel usageFuel consumption in vehicles is dependent on the size of the vehicle, the size of its engine, the amount of weight the vehicle is transporting and the distance between major stopping points. Even cars with remarkable miles-per-gallon performance suffer decreased fuel efficiency in city driving involving many stops and starts. In addition, starting a vehicle consumes a lot of fuel. Cars obtain their best gas mileage when traveling on an open highway. The transmission of the vehicle also impacts fuel mileage, with manual control vehicles getting better gas mileage than automatic cars.A number of factors determine the fuel efficiency of any vehicle. Variables such as car size, transmission type, weight of the vehicle cargo and hybrid availability result in considerable differences in MPG across many models. Hybrid vehicle MPGHybrid vehicles use a combination of battery and gas power, permitting these lightweight vehicles to travel farther than their standard counterparts using the same amount of fuel. Among hybrids, the Chevrolet Volt and Nissan Leaf are the most fuel-efficient vehicles currently on the market, with both models delivering almost 100 MPG on city roadways.Non-hybrid vehiclesFor standard vehicles that do not utilize an electrical drive, the Mini-Cooper, Toyota CR-Z and Ford Fiesta are consistently among the most efficient vehicles from year-to-year. Lately, automotive companies are going to great lengths to produce more fuel-efficient vehicles in an effort to satisfy consumer demand, and the number of high-quality vehicles offering greater gas mileage increases with every new model year.Shopping for fuel-efficient vehicles is not a difficult task, provided you are aware of the factors in each vehicle that impact its fuel economy. In the current vehicle market, both standard and hybrid car models offer decent MPG performance, allowing you to save money while driving.