Today in a parking spot, I spotted a Volkswagen Golf 4 of which the engine was running and the air conditioner was turning at a high speed (hearable from outside) in order to cool down the car, but **there was nobody inside**.

I did not recognize whether a key was inserted or not. But had the owner left the car while no key is inserted, that could cause the car to get stolen easily, so that would be a moronic idea.

Maybe it was a car modified to keep the engine running somehow without a key inserted and with the doors locked.

### Is this a common car modification, if any?

If so, is any of you familiar with this?

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That could be very practical in summer, in order to keep the car's cabin cold while oneself is absent for a short time.

Running the car's engine for one hour with air conditioning enabled roughly consumes 1 litre/liter of fuel (0.26 gallons) per hour, which would be worth it.