Bro, I am the king of vandalizing shit and getting away with it. Used to do it to my enemies ALL THE TIME when I was a teen. A BB gun was my preference.
Wear nothing identifying and invest in a cheap ski mask or something. Buy a CO2-powered BB gun, run up to the car and start blasting. The deed is done in less than 5 seconds flat. Be sure to have your car parked nearby, engine running, in drive and with the e-brake on. That way you can sprint to your car, hop in and just release the e-brake to take off before anyone even realizes what you've done.
And whenever she has the windows replaced, blast them out again
Good luck
