Our group made it up to the trailhead in a rear wheel drive Toyota Sequoic and in an all wheel drive Acadia. Having said that, after being on a serious 4WD trip before I felt very nervous a few times and wished that we would have had a full sized spare and some rescue gear. There were two tricky dips in the road, with the worst one being approximately 3/4 of a mile from the upper trailhead. We went in on Wednesday night and drove to the trailhead then back-tracked to find a good campsite. The sites near the trailhead were taken until about where we ended up.
It rained Thursday afternoon (8/23) through Friday morning, then off and on Friday afternoon. The trail has a fair amount of rocks and pretty hard packed, so conditions weren't too bad. Except the two big dips were also muddy. But we made it fine. We did see an Outback or two at the trailhead.