I was thinking rich colonists (50$ or more etc) that had a long commute would have the ability to buy a car and drive it on roads... I know it wouldn't work with the new colonist rendering system but could be something interesting

Public transport. This is a very big one. Buses, Trains, Metro, Teleporters. Being able to build underground structures such as metro tunnels will be a huge step in the game and maybe even underground buildings (new update?) could be awesome to see, in order to make the best of space. With public transport, building commute ranges can be "copied" to each station if the line connects to a residential area. Just an idea. Seems like a major update but it would be awesome to see.