Do you deny such mandates impact the price of automobiles?
Another and larger contributor is loose fiscal policy, devaluing the dollar.
Using your example of a $15k 1986 Buick Regal T-Type purchased in July 1986; according to the CPI calculator would cost $44,493.15 today.
Add in the cost of mandates, [and subtracting for modern efficiency/productivity improvements (to lower the COGS) from automation and outsourcing], and we’re easily at $50k.
There are still modern sleeper bargains to be had, and such modern sleepers typically exceed the performance, safety, and comfort of elite performance cars from the mid-1980’s.