I rely on my car to haul, well, everything. The Prius V without the rear seats is very roomy, but plywood, lumber, ladders, beams, etc. just aren't a good match for the interior. The factory bars and mounting range just wasn't going to cut it. I really enjoyed this topic Prius v (Lowercase v for the Prius v wagon) Five - Custom Yakima 54" track and DIY instructions | PriusChat I dinked around for about a year and a half cogitating and making drawings. My objectives were maximum strength, full length support, and to be strategic about the number and placement of the holes I needed to drill in my roof. Let's start with the finished product: At the front corners I utilized the hole in the headliner through which the wiring for the visors passes to insert the nuts. At the rear corners I cut access flaps in the headliner with a utility knife, and in the center I pried back the headliner and found a cross bar through which I drilled my holes. I would have liked more cross bars but didn't find any I felt I could utilize for my setup. I used the shallow Unistrut for the removable cross bars, and 3/8 stainless bolts through the roof. The permanently affixed runners are White Oak. I was leaning toward 3M 5200 to seal the holes but got skittish reading up on how irreversible that is so went with butyl tape instead. I used some I had left over. If I ever (feel the need to) redo this I'll probably get some thinner tape, though it has flattened out over the past few weeks all by itself. So far the fuel economy penalty with 750# of lumber up there was about 9mpg. I can't detect any measurable fuel economy reduction from just the runners, or even a light load with the cross bars installed. I am very pleased. I don't think I'd do anything different were I to do it again. It is rock solid.
