Toyota’s Prius has been known to be the most fuel-efficient vehicle in the U.S. market for years and the automaker has kept that title with their 2016 Prius Eco. Well now it’s time for the Prius to step down because the Hyundai Ioniq hybrid’s Blue model is now the most fuel-efficient hybrid in the United States with a combined rating of 58 mpg.
When CarAndDriver asked Ioniq project members how they achieved this feat, they were directed towards a few design key points.
The engine runs lean and has the same thermal efficiency as the Prius at 40%. What pushes the Ioniq ahead is the engine’s long 1.35 stroke-to-bore ratio which keeps thermal mass to a minimum. To increase combustion efficiency, a 2900-psi direct-injection system.
Then there’s the battery portion of the hybrid and Hyundai’s battery-control strategy. They didn’t say much regarding this matter aside from claiming that their control algorithm is better than a competitors even if the same lithium-ion batteries are used.
Very little torque lost in translation thanks to the Ioniq’s dual-clutch automatic which has a torque-transfer efficiency of 95.7%, thus providing owners with better fuel economy and a closer connection to the powertrain.
Aerodynamics plays a large part as drag can increase a vehicle’s fuel consumption. All Ioniqs have a 0.24 coefficient of drag thanks to underbody shielding and brake calipers pistons retracts slightly. Hybrid and plug-in-hybrid models have additional grille shutters and the Blue models are equipped with special aero-optimized wheels.
Weight reduction is another way to increase fuel economy and the Ioniq lineup was put on a diet of aluminum hood, liftgate, and suspension components along with 54% high-strength steel for the core body structure.
Combined, these features managed to deliver the most fuel-efficient Ioniq the United States has ever seen.