If you happen to live in California or Oregon or somewhere else where the more unorthodox members of our fine society tend to congregate, you might already be familiar with the van life. It's when people exchange the luxury of living in a house that's actually attached to the ground somewhere for the freedom of living in the back of a van. As you do.

Unlike the classic RV crowd, van life folk aren't all retired, but are usually young enough for this kind of stuff to be acceptable to their peers. And they aren't cruising around in 45ft Winnebagos, but actually live in vans. You know, those things that are made for carrying around tools and stuff, not people's full-time bedrooms.

Maybe you're looking at all this and thinking "great! I'd love to save on rent! I'd love to be able to take my house to Burning Man! The whole zen mindset this lifestyle promotes is a great antidote to all the problems of the modern world!" If so, good for you. Follow your dream. But what if there's something holding you back from selling your boring old brick box and taking to the open road like a more exciting person? And what if that something is the mediocre driving experience of the typical van?

If only there were a way to have all the convenience of a house on wheels without sacrificing the joy of actually driving it around. I mean... maybe you could just live in a BMW or something?

I know what you're thinking. Crazy, crazy talk. Nobody's living on the back seat of a sports sedan. But the van life isn't about taking something out of the showroom and moving straight in. It's about taking something and converting it into the customized mobile home you want. Isn't that what freedom's really all about?

So which BMW is the best blank canvas for your new residential vision? Which is the block of marble just waiting to be carved into a road-legal crib? Are there even any that could realistically be transformed into The Ultimate Living Machine (sorry)?

Straight away we're going to have to discount any sedans and coupes, for obvious reasons. There's not enough room for yourself and your worldly possessions, no matter how committed to minimalism you are. So we're going to need something bigger, which means an SUV or a wagon.

An X5 is pretty big, and considering regular people houses also tend to be pretty big, you might think that settles the debate in favor of the SUV. But X5 bigness isn't usable bigness, at least when you're trying to build something you can live in. It's all height, but as you're going to end up sleeping in this thing every night, you should really be putting more focus on length. Plus, SUVs are top-heavy enough as it is, so just imagine how much worse it would get if you had a house up there, too. As the whole point of living the van life in a car is for the driving experience, we really can't look past a wagon for this.

The easy way out would be to suggest getting a new 7 Series with the extended wheelbase, taking it to a body shop and having it converted into a wagon. But that's not the van life. That's some high-budget shit right there, and a true commitment to the ways of the van means getting a bargain on something used and giving it new life. So we'll have to take a step down to a 5 Series Touring.

I'm thinking maybe an E39, which you should be able to find for a decent enough price. You've got a little over 6ft between the front seats and the back of the trunk, so once you've taken the rear seats out of your new living room (because obviously you're going to do that), there should be just enough space for a standard 75-inch mattress. I'd advise a small single, in part to leave more space for the rest of your stuff, in part because a car house is definitely single-person accommodation so don't even think about doing any of this stuff if you have a partner you're on speaking terms with.

Living comfortably in a car (or any other tiny house) is all about efficient use of space. In our case we have the backs of the two front seats going to waste. So why not go all 2007 Xzibit and eliminate that waste while eliminating waste with a seat-mounted garbage can? Having a place to sleep and a place to put your trash has really helped turn you car into a nice, cozy living space. You can probably already see yourself calling it home.

Unfortunately, our wagon doesn't have much headroom. You might be able to add a pop-top like a 70's VW campervan, but unless you do, you probably won't be looking at much more than 3ft of usable height. Needless to say, you aren't standing up in this thing. Finding space for storage is also going to need some creative thinking.

I guess you could raise your bed up about a foot, to create some storage space under it. It might get a bit claustrophobic sleeping so close to the ceiling, but you gave up spacious living when you decided to move into your car, so it's something you'll just have to learn to live with. And as you sensibly chose a single mattress, there should also be enough space left to the side of your new bed for some extra storage. A few boxes along the opposite side might be enough, leaving a passenger jet style gangway down the middle to make getting in and out of your pad a little bit easier.

There are still some pretty big questions that need answering, like what conveniences you're expecting in your new 120mph home. A bathroom is definitely out of the question, but what about a kitchenette? Perhaps a cigarette lighter-powered slow cooker? Just think of all the goulash you could make!

The more I think about it, the more sense it makes. Imagine taking your house through some backroads with a smile on your face, then pulling over wherever you want, eating some goulash and turning in for the night. Seriously. Imagine it. And you're still telling me you don't want to live in your car?