Yes, a car can be towed from a tow away zone even if you are sitting in it and have never left it. Most tow-away zones have signs posted that indicate that vehicles are subject to towing at all times, regardless of whether they are occupied. If you park in a tow-away zone and do not move your car before the posted time limit, your car may be towed.
It's important to be aware of the local laws and regulations regarding parking in tow-away zones. Even if you are sitting in your car, you must still comply with the posted time limits. If you are unsure whether a particular area is a tow-away zone, it's best to err on the side of caution and find another place to park.