Theft-proofing a convertible with no steering lock

disable run... like people mentioned, fake coil wire, remove rotor, etc.

THEN so it cant be towed

chain it to your house. use the chain that cant be cut with bolt cutters.

then they need a cutting torch and a rollback

they could still take it but they will be on video with the truck

I could still hook that car in 45 seconds. Helper jumps out of the cab as I back the truck in, heats the chain with a plumber's torch, then quenches it with liquid nitrogen as I line up the hoist. Whack it with a hammer, the link shatters like glass as I lift the car...he jumps back into the cab, I'm gone. Couple blocks away, stop to strap down the tires on the hoist & slap on tow lights.