A really great way to kill your catalytic converter, if you haven't already done so!!
AVGAS LL might say "Low Lead" on the tin - but it contains a lot more lead (TEL) than old leaded car fuel ever did!
If your car needs a very high octane fuel to counter "pinking" (pinging if you are west of the Atlantic) and has no catalytic converter, it is useable, as some amateur racers do.