>>57256707 wide is definitely possible, however I would learn to crawl before running a marathon. Lego gets way more complex when working with odd widths, though I see plenty of nice models on Eurobricks and similar.
8 wide I'd steer away from, unless it's a really heavy duty truck or something.
Here's a 6-wide 4 seater I made, it's got a lot of room in the back for luggage and stuff without looking disproportionately huge.
Also, once again, without mudguards. It's not difficult, if anything, it makes it easier since you don't have to reserve so much space for the mudguards.
