5 including the Brompton for us.
Nomad/dirtworker in the car, so they get hosed down before the trip back. They don’t get perfectly clean but enough that they’re not shedding mud everywhere when they get moved.
We have an alcove in the hallway that’s big enough for a lean-to bike rack (as pictured above). 3 below, one up high. An old bit of carpet sits underneath to catch any muck.
Ikea do nice long (2m+) cheap robust carpet runners that are perfect for the hallway between the front door and where we store them. Rubber-backed so even if I did bring a muddy bike in, it’s not going to reach the light carpet underneath.
Maintenance – I do it in the lounge, chuck down a couple of old double duvet covers to catch any grime.
Definitely less convenient than chucking a bike on a roof carrier and jetwashing outside your garage when you get home, but doable.