How to connect roads to buildings

I have notice u cant connect a highways to buildings. so my question is what better roads can u connect to buildings to make the cars go faster. because i have gravel roads and concrete roads and highways is there other roads u can connect to buildings

Concrete roads are the fastest that support building connections. Highways and superhighways can only interconnect to roads (of any type,) and the road stubs of train stations. The advantage is that they allow faster truck speeds.