My guess was the keyless entry remote, which I expect is now very close to 100% penetration in the US. I wonder if that was one considered for the chart.
I'm in the 0%! But in all seriousness, I think the problem here is that these were actually introduced back in the early 80s on high-end cars. So it took a lot longer than 7 years to become widely adopted.
This strikes me as utterly implausible, since the most likely way to get one of these is to get a new car, something that seems to happen on about a 10-year cycle based on the latest data.
It's definitely not 100%. Probably over 50%, but my car and many others I know of do not have it.