What does car rest mean?

[StTanner]

rest: Residual heat utilization function of the air conditioning system. 1. It can provide heating for a period of time after the engine is turned off, and then it will automatically shut down. 2. It is a kind of heat preservation for the car. When the vehicle is started again, there is no need to turn on the air conditioning system, just heat the interior temperature. Therefore, turning on the heating in winter is more fuel-efficient than turning on the cooling in summer. Precautions for using air conditioning in winter: (1) The working principle of air conditioning heating in winter is different from cooling in summer. Most of the heating provided by the air conditioning in winter comes from the excess heat generated by the engine, which is blown into the car by the blower. (2) Wait until the engine reaches a good temperature standard, i.e., between 80-90°C, before turning on the air conditioning.

[OLily]

After driving for 15 years, I finally understood this little symbol - REST is actually a function that uses residual engine heat for warmth when parked. Right after turning off the engine while it's still hot, pressing the REST button on the AC panel activates the blower to circulate radiator heat into the cabin. This is such a clever design - returning to a toasty warm car after winter grocery shopping without restarting the engine. Most German cars have this feature, with older VW models placing the button beside the knob while newer versions hide it in the infotainment submenu. It works for about 30 minutes max, but do check if your battery has sufficient charge.

[KingFitz]

As a car enthusiast, I really appreciate the practicality of the REST design. Essentially, it's a heat recovery system that utilizes the coolant temperature of around 90°C after parking to heat cold air through a heat exchanger. Unlike air conditioning heating which requires compressor activation, this function relies solely on the blower, making it more energy-efficient. It's particularly useful during northern winters when temperatures drop below -10°C – while waiting for half an hour to pick up kids from training classes by the roadside, the cabin temperature can basically be maintained above 15°C. However, it becomes ineffective once the vehicle has completely cooled down, and this feature might not be available in base trim models.

[OElias]

This feature is totally unnecessary in the south, but the REST button becomes indispensable when traveling to Northeast China. Press it when parking in the morning, and you'll return to a warm steering wheel. The principle is simple - the engine coolant retains enough heat to provide warm air for a while, which is much more economical than restarting the engine. Volkswagen's system defaults to 20 minutes, but using external air circulation shortens this duration. The downside? Be cautious with older car batteries - my old vehicle almost failed to start once after using this. While newer electric models have switched to electric heating, this waste heat utilization design in combustion engine cars is genuinely clever.

[McJohnny]

Every time I drive my colleague's BMW, I play with the REST button featuring the fan logo. The engineer told me this system costs less than 200 yuan, just adding a delay relay and an air valve control module. The best part is it doesn't consume fuel, using residual heat to save about 5% fuel consumption after parking. Last week at minus five degrees in the parking lot, the temperature only dropped 3 degrees within fifteen minutes during testing. But remember to turn on the heater before shutting off the engine, otherwise the pipes will be full of cold air. Now most domestic cars priced above 100,000 yuan are equipped with this feature, though the icon is often overlooked as it's hidden on the third page of the air conditioning menu.