In the past few years, 40 miles per gallon has emerged as the definitive benchmark number for fuel efficiency. Almost every mainstream small car hits this mark, and even some larger midsize sedans are reaching 40 mpg these days. But you don’t have to spend big to save big at the pump. We set out to find the cheapest cars for sale that achieve 40 mpg in EPA testing (which measures highway, city, and combined driving), and were surprised to find exactly ten 40-mpg cars that cost under $20,000. It’s worth noting that many of the cars below require a special powertrain combination or fuel economy package to hit 40 mpg, but each listed price includes destination charges and represents the exact configuration needed to achieve 40 mpg.