On our real-world 75 mph route, the 2023 Mercedes-Benz S580e has the most extended electric range of any plug-in hybrid. The car cost over $120,000 and could go 58 miles on electric power alone. This was 14 miles farther than the closest PHEV and 12 miles farther than what the EPA said it could do. The big 22.7-kWh battery in the plug-in S-class is mostly to thank for its high test score. Plug-in hybrids are better than electric cars in the following ways: If their batteries run out, they can keep going with their internal gas engines. When it goes on sale in 2023, the Mercedes-Benz S580e will be one of the few PHEVs that can go more than 40 miles on electricity alone. On our 75 mph highway trip, it also had the most extended real-world electric range of any plug-in hybrid we’ve tried. The farthest place The EPA says the plug-in S-class can drive 46 miles on its power. In our tests, the $100,000 car beat the standard by 12 miles, going 58 miles on electric power alone. This is 14 miles better than the other plug-in hybrids we’ve tried. The 2024 Volvo V60 Polestar Engineered came in second. It went 44 miles, which was three miles more than expected. The only other plug-in car to go over 40 miles was a 2018 Honda Clarity, which went 41 miles. Since this test began in 2016, we have looked at more than 45 PHEVs. Let’s talk about how we did things so you can see how we got here. All of the tests are done on the same 200-mile out-and-back loop in Ann Arbor, Michigan, at a speed of 75 mph, confirmed by GPS. We do this with great care, using speed control and setting the automatic temperature control to 72 degrees. Plug-in hybrid cars must take extra steps, like ensuring the battery is fully charged before going on the route and tracking how many kilowatt-hours (kWh) it took to charge the battery after the loop. The PHEV’s EV range on the highway is measured when the battery dies, and the gas engine starts. Help for Big Batteries So, what makes the S580e’s real-world range the best? Hankook Ventus S1 Noble 2 all-season tires on our test car are pretty sticky (0.85 g on the skidpad), but Mercedes is proud that its long, low body has a low drag coefficient of 0.22. A set of tires with low rolling resistance could improve gas mileage even more. The massive battery is the main reason the vast car has such a fantastic range. The Mercedes battery can hold 52% more power than the Volvo V60 cell, which only has 14.9 kWh. The plug-in S-class did not go 52% farther in our test. Its economy was also hurt because it weighed 5606 pounds (1112 pounds more than the V60) and had a heavy curb weight. But in our real-world test of electric range, the S580e is the first PHEV to go over 50 miles, let alone almost 60. It also did very well when the battery ran out. For the rest of the run, it averaged 36 mpg using only its 362-hp turbocharged inline-six engine, which is much better than the 29 mpg highway rating the EPA gave. With 510 horsepower, the plug-in S-class keeps up with the V-8-powered S580, going from 0 to 60 mph in 4.2 seconds and finishing the quarter-mile in 12.6 seconds.
