TechSpot published Four Cores for Ultrabooks: Core i7-8550U 8th-Gen Intel Core (Kaby Lake-R) for Low-Power Laptops A quote from the article:

This has been a big year for Intel low-power mobile chips. For generations we?ve put up with sub-10% year-on-year performance improvements, having Intel focusing on better efficiency and longer battery life. However, with AMD hot on Intel's heels and set to launch their own ultraportable processors in the near future, Intel has decided that the time for incremental improvements is over.
With that, Intel's low-power mobile chips have finally transitioned from a dual-core to quad-core design for the first time. This has been achieved while keeping within the same 15-watt TDP as previous low-power U-series chips, essentially allowing for a big jump in performance without a corresponding hit to battery life.
Before we discuss the specific changes to Intel's new processors, let's talk a bit about the basics, in particular Intel's confusing product line for 2017.

 Four Cores for Ultrabooks: Core i7-8550U Review 8th-Gen Intel Core (Kaby Lake-R) for Low-Power Laptops @ TechSpot