Yesterday I was looking at the scheduled on-line races and noticed that for a race at Macau with TCR cars I was offered the option to select among the cars I own. I have some models from various years, not all of them. I was able to select almost all the cars I own including the Peugeout 308 from 2018, but the VW Golf and Audi R3 LMS from the same year were not available, I was told I had to buy them. I have only the 2018 pack, not the same models in the following years (there is no pack for them at the moment, so I did not buy them one by one yet). Does this mean one has to own the model of the most recent year available for a given model to be able to race with it in TCR races?
I haven't looked into the car selection screen of those races yet, but for GT3 races (which are similar to TCR races in terms of car selection), you can use 'older liveries' as well. I can also remember that from the last races I did in TCR. However, things may change. If you purchased the WTCR 2018 pack including the Golf and you can't select the Golf for registering in the race because only the 2019 liveries are allowed, that sounds to me like something went wrong in setting up the races.
here the cars apparently are not exactly identical: if you own the 2018 version you have to pay 50% for the models of the following years, not just the price of a skin. It applies to the Giulietta, i30, Golf, Cupra and Audi R3, not to the Civic.