What takes all the time is rolling everything down. The rollers that come supplied are poop. They end up breaking & won't last for a whole vehicle. Can't put any real weight behind 'em.
I have 3 sizes of rollers. The smallest was originally for doing wallpaper, about 1.5" wide, 1.5" diameter. Wood roller. It's cheap, too, but better than the supplied ones. Better handle & axle. Good for tight areas.
The next one has a nylon wheel & a long two-handed wooden handle. Roller about 3" wide, 2" diameter. My usual weapon of choice for doing interiors. Gets into most of the spots in among all those bumps & dips in a interior floor. I can lean on this one pretty good. Really sticks that stuff down & rolls out most bubbles.
Then I have one that also has a nylon wheel, but it's about 6" wide, 2.25" diameter, with a 30" long handle. Good for doing large flat panels on the bench, fast, or when I'm doing the inside of trunks or van walls.
I've also used those really narrow rollers for putting in the plastic beading that holds in the bug screens on screen doors. The do get into the corners, but mostly they just cut the foil. As long as that gets hit with some aluminum tape, it should be fine.
Make sure the floor's clean. Open both doors & blow the majority of the crud out. (wear googles!) Vacuum the rest, then wipe the floor with some reducer or some other type of degreaser that doesn't leave a film behind.
If you have a sound system, get all the wires straightened out. Keep the power wires away from the speaker wires. Don't cover them with the deadener.
Start from the center & work out to the edges when laying the stuff down.
Don't try to cover as much as possible at once. Smaller pieces are way easier & a whole lot less frustrating to work with. Anything longer than about 2' can be a PitA! Once the stuff sticks to itself, it's awful damn hard to get it apart without screwing the piece up. It's expensive enough as it is!
I like to overlap pieces. Not a lot. Maybe by a 1/4" or so. Other guys will butt pieces together then go over the seams with aluminum tape. Mmm, too finicky! I find overlapping to be easier & faster. No-ones gonna all see this anyhow!