Well maybe not the freezer but some other domestic Faraday Cage.

He explained it like this: In a normal scenario, when you walk up to a car with a keyless entry and try the door handle, the car wirelessly calls out for your key so you don't have to press any buttons to get inside. If the key calls back, the door unlocks. But the keyless system is capable of searching for a key only within a couple of feet.

Danev said that when the teenage girl turned on her device, it amplified the distance that the car can search, which then allowed my car to talk to my key, which happened to be sitting about 50 feet away, on the kitchen counter. And just like that, open sesame.

http://www.brisbanetimes.com.au/digital-life/consumer-security/why-keeping-your-keys-in-the-freezer-can-stop-thieves-breaking-into-your-car-20150415-1mm25p.html

I wonder if any crims are doing this here in 'straya?

Some kind of wireless repeater I would think

How the hell is this "power amplifier" device meant to work? I suppose you would use it by attempting to open the car door while the device listens for the car's interrogator signal, then it clones and re-transmits that signal at higher power to reach the key. Does the key then have enough transmitter power to be heard by the car at several tens of metres? Or maybe the thieves' device has a high gain antenna, catches the key's response to the cloned signal and retransmits it for the car...

Car keys use RFID and can have a pretty decent range:

http://www.rfidjournal.com/faq/show?139
"Battery-powered tags typically have a read range of 300 feet (100 meters). These are the kinds of tags used in toll collection systems."

I suppose the antennas in cars are quite small and aren't pumping out much power as they only want them to work up to a few feet.

These devices must be a decent sized antenna coupled to electronics that replicates the RFID signal pumped out by the car. Then you'd probably need a big battery to go with it.

The article mentions car manufacturers are looking to implement systems to stop this. I'm surprised they didn't already have some sort of latency check to make sure this didn't happen. I don't know if you can do that with RFID.

key less car starts are probably the least wanted feature in cars since car inception

Yup. What do they save? Out of all the tasks of owning and operating a car, i've never once said 'gee i'd like to not have to put keys in the ignition and turn them once to start the car'.
What a load of s***

I'm just going to leave this here.

Note: This is a 'remote started' car, and the guy who stole it had a 'knock off' key reprogrammer and a blank fob.

I'm sure BMW will have made modifications to their systems to prevent this (I'd certainly f***ing hope so anyway) but this was the deal breaker for me. I do not want to own a car I don't need some sort of mechanical device to start it with.

This mob? You mean you sell it?