Editing Power window (section)

== Operation ==
Power windows are usually inoperable when the car is not running. This is primarily a security feature. It would be a simple thing to allow electric power windows to be operable when the ignition is turned off, however it would also make the car much easier to steal. Some systems offer the compromise of leaving power applied to the windows until a passenger door is opened at which time the window power is removed.

[[Hydraulic drive system]]s could lower the windows at rest, since pressure from the hydraulic system was merely released to lower the window. Raising the windows required an electrically operated [[hydraulic motor|pump]] to operate and introduce pressure at the appropriate [[Hydraulic cylinder|cylinder]]. These systems also required pressure lines to each cylinder (in the doors, as well as on certain cars, to the [[power seat]] and a power operated [[convertible (car)|convertible]] top). Because of the complexity, the system could also leak fluid. 

Many modern cars have a time delay feature, first introduced by [[Cadillac]] in the 1980s, called "retained accessory power". This allows operation of the windows and some other accessories for ten minutes or so after the engine is stopped. Another feature is the "express-down" window, which allows the window to be fully lowered with one tap on the switch, as opposed to holding the switch down until the window retracts. Many luxury vehicles during the 1990s expanded on this feature, to include "express-up" on the driver's window, and recently, some manufacturers have added the feature on all window switches for all passengers' convenience. This is done by activating the switch until a "click" response is felt.

Power windows have become so common that by 2008, some automakers eliminated hand crank windows from all their models. So many vehicles now have power windows that some people no longer understand the (formerly) common sign from another driver of using their hand to simulate moving a window crank to indicate that they wish to speak with someone when stopped at a light or in a parking lot. The 2008 [[Audi RS4]] sold in Europe, however, still has roll-up windows for the rear doors although its counterpart sold in the U.S. has power windows for all doors.<ref>{{cite journal|url= http://www.caranddriver.com/comparisons/2007-audi-rs-4-page-2 |title=2008 BMW M3 vs. 2007 Audi RS 4, 2008 M-B C63 AMG Comparison Tests |page=2 |journal=Car and Driver |date=December 2007 |access-date=26 December 2012}}</ref>