Ask the Mechanic: Can I save fuel without switching off AC?

Hello DM, there are other ways to save energy besides switching off the car air-conditioning such as driving sensibly and non-aggressively, maintaining the engine, driving on correctly inflated tyres with good treads, planning your journey and avoiding unnecessary idling at long stops. Also, do not overload your car and use cruise control. 

Aggressive acceleration and jack rabbit stops increase the car’s fuel consumption as it keeps the transmission in low shifts and the engine revolutions in the fuel thirsty high bands.

Drive moderately, accelerating gently and braking gradually during normal driving. Engine maintenance with recommended engine oil and spark plugs will help your engine run lighter and burn fuel more efficiently.

This benefit can be leveraged if you fuel your car with fuel that is designed with fuel system cleaning (detergency) and engine efficiency improving (lubricant) additives. This will not only protect your engine but give you better fuel economy. 

Correctly inflated tyres reduce rolling resistance and fuel waste load on the car while good treads reduce the engine effort to move the car. Worn out tyre treads cause skidding or loss of traction and the engine has to turn faster to move the car. This puts a toll on your fuel. 

To help matters you can also avoid overloading the car with unnecessary luggage. Use of the cruise control when driving on the highways helps you maintain constant speed without frequent accelerations and deceleration. This will give you better fuel economy.

What is a keyless car? And if you have to press the key fob to open it, is it still a keyless car? Brian

Hello Brian, a keyless car is one which can be accessed and started without inserting a key in the door lock or ignition switch.  

This is also called keyless access or keyless go. The keyless car uses a remote fob or smart card which is detectable by the car’s security system as long as it is within a certain distance.

The keyless car allows you to use the buttons on the remote key fob to open or lock the car should you choose not to use the smart touch sensitive door handles. You can also start the car by pressing the push to start button.

What is limp home mode and how do I get my car out of it? Tracy

Hello Tracy, limp mode, is a safety feature designed to activate reduced performance when it detects a major fault in the transmission or engine. In the limp home mode, you are able to drive with reduced power, to allow you drive to the garage.

This feature is found in many post 2000 modern vehicle models. To get your car out of limp mode, you must fix the faults that caused it. This could be faulty components, sensors or circuits. A full diagnosis at a competent garage will help identify the causes and resolve them. Technicians can reset the car computer to switch off the limp mode.