As you might expect, the most fuel-efficient vehicles are generally the smallest and lightest cars. The 2020 Mitsubishi Mirage — with its tiny three-cylinder engine, subcompact size and no-frills interior — achieves 39 mpg combined when equipped with the continuously variable automatic transmission. In the world of hybrids, the Hyundai Ioniq Hybrid is rated at a staggering 58 mpg in its ultra-efficient