I am quite familiar with reproducible examples and thought I was providing one when I provided a specific data set and the things that I had tried. Thanks for catching the typo, though. I, of course, meant leveragePlots, although there is a leveragePlot function in car as well that seems to map to the same code.
I too was able to run the example in the help file, but was not able to reduce it to a simpler example, although as you see I tried several things. The example in the help runs the lm() inside the leveragePlots() function itself, which is certainly not the way that users would use the plot. Since it's a diagnostic plot, most people would have run a linear model and would then want to produce the plot afterward, as I am trying to do.
Your reduced example may not work as you've requested the Y variable (prestige) rather than one of the X variables (income, education, etc), and leverage plots are used on the X variables. That may be one reason you are getting an error.
I very much appreciate the help but am not sure what your post is trying to tell me -- that the help page works but other things don't?