Hybrid technology has found its way into more and more cars which has helped to bring cost down slightly. Not all hybrids are created equally, though. There are "mild" hybrids that use the battery to assist the internal combustion engine and "full" hybrids (sometimes called "two-mode hybrids") that can run exclusively on battery power under certain conditions. Even a little help in the miles per gallon (MPG) department can make a big difference, so mild hybrids still consistently deliver better numbers than their gas-only counterparts, but the gaudy efficiency numbers are still reserved for the full variety.
Toyota brought the hybrid to the masses with the Prius which far outsold the competing Honda Insight due to its four doors and back seat. Drivers don't like to compromise, and Toyota delivered high mpg along with cabin room and amenities in the Prius, and it continues to satisfy drivers to this day. The third generation Prius topped the 50 mpg mark in the city with significantly tougher EPA testing standards than in previous years making it the top choice for versatility and efficiency.
Honda capitalized on what it learned from the early Insight program and developed several of its best sellers into mild hybrids. The Civic tops the mild list with a 40/45 city/highway split.
The Ford Fusion, like the Civic, is a mild hybrid that also has a conventional combustion engine counterpart. The premium for upgrading to the hybrid is steep, but it offers a very solid 41/36 considering its size and its bevy of standard equipment. All those extras add weight as well as convenience which keeps the Fusion's numbers own a bit.
Nissan opted for consistency with its mild hybrid entry and as a result, the Altima has the narrowest spread between city and highway mpg on the list. Whether you're on the highway or putting along on surface streets, the Altima reliably delivers about 34 mpg.
