Create virtual subdomain

I’m running a multisite on example.com using (virtual) subfolders. It’s working fine as it is but I want to take another step in expanding my business. Right now the url would look like: example.com/subsite1 and example.com/subsite2.

I would like to have a “branche” in the virtual structure: example.com/cars/subsite1 and example.com/cars/subsite2.

It is possible to change the siteurl etc to /cars/subsite but then the example.com/cars/subsite1/wp-admin is no longer working.

Any ideas for this? I appreciate it!
Bas