I was at Home Depot a few weeks ago and watched two guys load three carts full of lumber (enough for an entire deck) onto the back of their pickup truck. I am pretty sure it was a half ton truck, and the wood probably weighed close to two tonnes. It was obviously overloaded, but they made it out of the parking lot ... unlike these guys:
Our SUV can safely carry a load (people + cargo) of 1200 lbs, which isn't that much when you consider the weight of lumber, concrete, etc. It works well for most small projects, but I have learned that it is best just to get large quantities delivered. Most lumber yards will deliver for free, but even the $75 or so Lowe's charges is worth it in my opinion.