Summary
Likely due to the move to "ReactVision", all the example links on the following page are broken:
https://viro-community.readme.io/docs/examples
They all point to:
https://github.com/viromedia/viro/tree/master/js/ARDrivingCarDemo
I could not find the corresponding folders in the new ReactVision organisation
Edit
Correction, found them under here:
https://github.com/ReactVision/ar-demos
(Although they all seem out of date and require a Viro key? - pre-open source?)