How to protect your car from your kids?

I actually have a 100,000 volt fence around my house so I can offer some advise. When you buy the fence they are set to "pulse" on and off every 0.5 seconds or so. So if an intruder touches the fence it will not actually kill them since when the electricity pulses off they jump back. If the electricity was constant then there is a chance of them gripping the wire which might harm them. There is very low amperage as well so there really is little risk of death. Another nice thing about the fence is when the system detects a ground/short it sounds an alarm so you would know when someone got too close to the Porsche, and then could inflict secondary discipline measures. My system also sends an email to my BlackBerry when the alarm sounds which includes a photo of the area. This would allow you to make sure the proper intruder received the secondary punishment.

Cats can smell electricity (I am told) so they tend to avoid it which can help reduce paw prints. The installers told me that a dog might touch it "once". So, depending on how smart the children are, I image they would not touch it more than once either. However, considering that the children are not following verbal instructions a few shocks might be required in order to acquire proper respect for German products. The fence also makes a nice little snapping sound at times which tends to remind people not to touch it although my gardener has been shocked a couple of times.