I’ve wanted this so bad and I’m glad I waited because I almost bought it a few days ago. It dropped from $39.99 to an even $20 with GOLD so I snatched it up.
I am very glad you mentioned this! I check the Deals with Gold page frequently, but I had not seen this yet. Trying to buy cars for FM5 pops up the Car Pass page so often for me - this is welcome news indeed.
FYI, if you are a Xbox Rewards member you will get $2 back in rewards points for buying the car pack ($19.99 or more purchase on an add on is the qualifier) and you can get $1 back for unlocking 10 achievements in certain racing franchises including Forza, F1, the crew, NFS, and project cars. Also, if you buy a qualifying racing game for $59.99 or more you get back $5.
Also, the rewards offer ends on July 31st and the Car Pass sale will end Tuesday morning.