Yeah and your '66 Mustang might have died on the way home from the lot! Quality in manufacturing (planned obsolescence aside) is so many light-years beyond what it was even 30 years ago that it's hard to compare. A Yaris may cost what a Cadillac did in '67, but the Yaris is going to last 200k miles without blinking, and with the most minimal care possible. Value is difficult to judge, because we all want different things, but I think cars are objectively better value now than then (subjectively speaking, of course).
To be fair, the Beetle is priced for those same hippies that now have more cash. Here are some cheap cars in 2016: Nissan Versa: $11,990; 66' adjusted: $1,617 Mitsubishi Mirage: $12,995; 66' adjusted: $1,752 At $1,352 the entry Beetle was indeed about $10k adjusted in 66'. But the car that bears the name is not targeting the same market now. Even so, if you got the squareback with a sunroof, your 66' Wolfsburg Beetle set you back the equivalent of $14,658. The price of cars is up some, but I don't think the affordability has changed too much. Especially when you consider that the quality of today's cars leads to a used car market with more cars that have life in them. Chevy Spark: $12,660; 66' adjusted: $1,707