I hardly think I gave the story justice, since it is based on my memory from something like 20 years ago or more and I am sure I am misremembering the specifics.

But to address the points that were raised:

It is a convertible and plastic does not do well in the sun. Then next year the company decides that they can save 50% on manufacturing cost by using a cheaper and thinner plastic, which would only last 10 years, rather than the decades of the alloy it replaced originally, but that is more than enough time for any car. Then soon after that the company decides that 10 years is still too long and they can save even more by.....

First a digital clock, then a digital clock that gets wifi updates, then a digital clock that tracks and transmits your locations, then a digital clock that won't work unless the company sends a heartbeat code, then...you get the idea...it is a slippery slope.

The ending works well because everything in the car is handmade and overengineered, and the "improvements" are all cost-saving measures. In doing so, he ends up making the car nothing like the original and nearly the same as the cars the maker was reacting to.