Two Hyundai Ioniq hybrid models have achieved fuel economy ratings from the U.S. Environmental Protection Agency that surpass their Toyota Prius counterparts in highway driving as the most fuel efficient in their category.

The 2017 Hyundai Ioniq Hybrid achieves 55 mpg in city driving, 54 mpg on the highway, and 55 mpg in combined driving, while the 2017 Toyota Prius achieves 54 mpg in the city, 50 mpg on the highway, and 52 mpg combined.

The Hyundai Ioniq Blue, a high-mpg variant that's similar to the Prius Eco, achieves 57 mpg in the city, 59 mpg on the highway, and 58 mpg combined, while the Prius Eco achieves 58 mpg in the city, 53 mpg on the highway, and 56 mpg combined. The Ioniq Blue receives a special tire-and-wheel package and other add-ons that increase fuel economy over the base model.

The EPA has also rated the Ioniq Electric at 150 miles per gallon equivalent in the city, 122 mpge on the highway, and 136 mpge combined. The Ioniq Electric's 124 miles of range puts it in the second tier of battery-electric vehicles after Tesla's Model S (up to 315 miles) and Model X (up to 289 miles), as well as the Chevrolet Bolt EV (238 miles).

The EPA hasn't released ratings for the Ioniq Plug-In Hybrid, which Hyundai says will deliver 600 miles of range when it arrives later this year.