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.
All of the other stuff - better acceleration, air bags, automatic transmissions, A/C - those are refinements on a capability that fundamentally didn't change. They both drive on roads at around 60 mph at approximately 25 mpg.
They're cool cars but today's $70k luxury cars are faster, stronger, more reliable, and functionally better. The old Caddies do look damn good, but I'll take a DOHC versus an OHV any day.
My point is that the technology has clearly progressed. To your point, maybe not exponentially, true. But there has definitely been a whole heap of engineering work over 60+ years that has resulted in unequivocally better, more reliable, markedly different vehicles.
Obviously, the field where exponential growth is/was sustained over a significant period is chips/microprocessors. Miniaturization is well-know as the key to this.
Information processing so-far is all that has benefited here. But existence of biological organisms, constructed from cells existing on a tiny scale, shows that miniaturization could be applied to other functionalities. There's no reason to think we're near that now but the situation does invite us to imagine it in theory.
The first search result I found had this: "we track four key global crops—maize, rice, wheat, and soybean—that currently produce nearly two-thirds of global agricultural calories. We find that yields in these top four crops are increasing at 1.6%, 1.0%, 0.9%, and 1.3% per year, non-compounding rates"*
Another example is fuel efficiency of cars? Although that has hard limits.
Sure, nothing like electronics, but over decades slow compounding of small amounts does matter to us all.
* https://journals.plos.org/plosone/article?id=10.1371/journal...
Well, not exactly. Both Robonaut and Baxter used series-elastic actuators. But Robonaut didn't invent them. This is kind of like saying that a lot of the tech from the lunar rover ended up in Tesla's. Sure, they both used electric motors and batteries. But Tesla's existence is in no way dependent on the lunar rover.
Cars may be a good model here. But I would argue that current generation robots aren't Model T's. 1960'-era industrial robots were the Model T. Current generation KUKA's are 1950's Cadillacs. Cars of today aren't exponentially better than a 1955 Caddy. The period of rapid growth in robotics (on the hardware side) started a while ago, and it's probably approximately linear.
Robonaut is the Lunar Rover. It's awesome, but it isn't at all clear whether any of that tech addresses a commercial market.