The DEM provider they integrated, Mapterhorn, looks great at a cursory glance. They’ve managed to source and package a ton of the free high res elevation data into one dataset for easy consumption.
Example: this DEM thinks there is a local discontinuity where a cyclist will ascend at +22% where this street crosses a buried freeway. https://graphhopper.com/maps/?point=37.80737%2C-122.279329&p...