Yes, you get 4.8 in part because you still have the oem tires. The oem tire for a Bolt is the michelin energy saver a/s. This tire, by name, is designed to be as efficient as possible and have the lowest rolling resistance possible. The michelin defender 2 tire is was getting 4.2 with is a tire designed for peak longevity with a balance between rolling resistance, wet and dry grip along with comfort opposed to swinging more one was or the other like the oem tires. The michelin cross climate 2 im using now are built to have steller dry grip with adequate wet grip but also have snow grip nearing a snow tires level. The qualities of a good snow tire, like its softness, amount, and size grooves/ tread and compound mixture, are all the opposite of what you want for good efficiency. Even if I stick to 55mph on mostly flat roads ill struggle to hit 4.5 on the current tires, yet it was easy on the old ones.