Cars with smart key entry system are the ones most at risk. Regular remote keys emit signals when clicked only. Which makes it a little harder to get the signal on their device.
However, smart keys are always emitting signals, if your car is parked outside of your house then they know that the key is definitely nearby, they'll walk around the house to get the trace of the signal, once the device detects it, they'll go back to your car and the device will mimic the same signal to your vehicle. And just like that, boom your car is unlocked and ready to be push started.
I think the best way is to install a kill switch inside your car, if you do it properly. Then the vehicle will stand still and it won't start.
Here's how to do it:
