A couple things jump out at me (in the new version of Night Ride):
*Does our car have to become a non-descript sedan? Since we're the only ones on the road, and thus have nothing to blend in with, can't we have something a bit . . .cooler? :)
*"Boot" is primarily a British term, which could limit your audience.
*Under "Major Threat: Somnabulism", I think you have a typo that's accidentally giving the person a superpower. Humans need about 8 hours of sleep every 24 hours (more under stress), but someone taking this flaw only has to sleep 8 hours out of every 48.
* On page two, one of the items is amphetamines, enough to keep a person awake for six months straight. Unless they're magic (which is possible), that's a very, very bad idea. In sleep deprivation studies, people start to get . . . well . . . psychotic, after about three weeks without sleep. You become emotionally unstable, can't learn anything new, and start hallucinating (serious, hardcore, LSD-level hallucinations, not some penny ante stuff).
*Right now, "Night Ride" just sort of . . . stops. I think you need some sort of climax or final challenge, to cap off the experience. Another car comes out of nowhere, and somehow you just know only one of you can escape. A roadside map, that leads you to a place where you'll have the chance to confront That Which Follows, or trap it. Some sort of last minute sprint to the finish line, as That Which Follows pulls out all the stops to catch you . . .
Something that makes That Which Follows truly the "last boss", not just some minor threat. A capstone, to the whole experience.
(Also, I'd point out that some people might prefer to stay on the Road forever - no traffic, no cops . . . interestingly weird. . . For a lot of auto enthusiasts, it'd be the chance of a lifetime - assuming you can ditch That Which Follows, and maybe find a cutie to ride shotgun. . . )