kill switch
Lot of good suggestions , but locking your hood and a hidden battery disconnect
switch or hidden coil kill are your best bet. But most important is locking the hood down. Any good mechanic or thief can start your car from under the hood . I think the real pro scum bags just tow them or trailor them away. I hate thieves. Got robbed last december , still not over it !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!