It works!
I just have the free version of the app too... and an old iPhone 5.
I was on the side waiting to see if the CarPlay thing came to fruition first. I shall now upgrade to the premium membership to gain access to the crazy amount of high-end maps that come with the premium membership.
It basically just looks like a regular map in free mode. I could not type in an address with turn-by-turn directions. However, the basic map was pretty darn detailed. Especially with things off of the beaten path.
Also, I imported my track labeled "Yellowstone" for a trip I am attempting to plan out. It showed perfectly fine. So I will map out the Alpine Loop in Colorado and White Rim Trail out in Moab, UT. When we make the trip to Yellowstone (seeing several other parks on the way) I will be able to follow my pre-drawn out trails to follow.
AS AN IMPORTANT SIDE NOTE:
A few months back I was ferrying a helicopter from here in Elizabeth City, NC allllll the way up to Kodiak, AK. The only two apps that worked EVERYWHERE we went were...
1) Gaia
2) Navionics
These were the only two apps that use the GPS chip in my phone. They even worked way out in BFE in Canada and waaay out over the ocean.
Pic for proof that the app works in CarPlay. These are the apps that I have that work with carplay. (I could not take a pic once I opened the app) Yes... that is a YouTube... however it does not play on the screen. I can just hit play/pause with the screen. However, you can watch youtube and other apps if you jailbreak your phone... which I will never do.