Board Thread:Game Discussion/@comment-30836563-20190221055639/@comment-27170954-20190221161747

They won’t ever add new tracks to existing series except in rare instances. Users not wanting to recomplete old series is one reason, thought I think that is a silly one myself

Real reason is tracks are by far more expensive than cars. Tracks only get added to new series because the price users pay for new cars pays the costs of track development. Adding new tracks to old series probably would not generate enough revenue because the cars are already bought and paid for.

Adding new series with old cars alsohas limited benefits because the cars users would want to run on new tracks are likely already upgraded. Thus, no revenue for developers.