> Cars of today aren't exponentially better than a 1955 Caddy.
You're talking about cars that cost around $70k in today's dollars with 6.0L V8 carburetted pushrod engines that go 0-60 in 15 seconds, no standard AC, 4 speed transmissions....they looked cool, but you can buy a $30k Infiniti nowadays that is lighter, has just 60% the engine displacement, has fuel injection and variable valve timing/lift, goes 0-60 in 5 seconds, has 4 wheel disc brakes, a 7 speed transmission...the list goes on. Oh, and standard A/C.
I'd say that getting 3x the acceleration at half the price, with multiple times more reliability (try driving a 1955 Cadillac 300k miles without rebuilding the engine or heads), traction control, airbags, intelligent cruise control, and all the modern comforts is indicative of rapid growth. And it keeps going! Now we are seeing electric production cars and autonomous street legal vehicles.
Exponential? Maybe not. But aside from computers, it's hard to think of technological developments as exponential. They tend to be intermittent, with advances coming in fits and starts.