The example of the cars is so completely bogus that it ought to be embarrassing for a physicist (which Locklin is) to have written it; one would expect them to know better.
It's about like saying:
- between 1900 and 1950 we invented all this awesome new technology
- but the information density of printed books (words-per-page) has remained roughly constant from 1950 to 2000
- ergo the rate of change must be declining
...in other words, compare:
- in column A: an unqualified sense of "rate of progress" over some time interval
- in column B: a product whose performance on some metric is substantially constrained by some combination of physics and rigid human factors
...and then point to lack of substantial improvement in the product's score on the metric in column B as evidence for the deceleration of progress; it is at heart only a qualitative improvement but there's no radical improvement to be had in that area, so looking to it and wondering "why no radical improvements in the information density of printed text?" says more about you than about what's happening.
Now, why the car example is bogus:
There's only so much energy in a gallon of gasoline, and fuel-efficiency is thus bounded to a pretty narrow range of variation.
Modern cars are larger and heavier than equivalent product categories of yesteryear, mainly in response to safety regulations.
Just look at the Nash Metropolitan (conveniently parked in a standard USA parking space for size reference):
http://en.wikipedia.org/wiki/File:Nash_Metropolitan.jpg
Or if you're not so good at depth perception:
http://latimesblogs.latimes.com/.a/6a00d8341c630a53ef01156fb...
(next to a cooper mini for comparison).
There's no mystery here: the 40mpg car he picked out of the past got 40mpg b/c it's a tiny car.
This isn't a case of some technological triumph of our forefathers being abandoned by decadent successor generations; it's a case of the laws of physics dictating the range of possible cars, and there being not all that much stateside consumer demand for microcars like the metropolitan.
So yes: cars today are little different in fuel efficiency than cherry-picked microcars of the 60s and 70s because the laws of physics haven't changed between now and then; we're not driving 100mpg micromachines because no one wants to buy them (yet).
I'd wager a fair amount that in a universe in which we were all driving microcars good old Locklin would be bitching about the forgotten musclecars are of yesteryear, along the lines of his concorde complaint in the same article.