1. Your car might run smoother

If you’ve ever driven a car built in the ’80s or earlier, you’re probably accustomed to twiddling your thumbs while the engine warms up. Why? Older cars relied on manual choke control systems and carburettors (fondly known as carbies) – devices which mix air and fuel in the engine.

A ‘choke’ was used for cold starting and, on some vehicles, required manual operation, which sometimes proved to be temperamental if the adjustment wasn’t correct.

According to RAA’s Technical Advisory Service Manager Andrew Clark, when the carbie didn’t get the right mix of air and fuel in the engine, there was potential for the car to “stall, misfire or lose power”.

“Instead of heading straight out onto the road, motorists formed the habit of letting the engine warm up a bit first, rather than face potential driveability issues when the engine was stone cold,” he says.

The auto industry eventually did away with carburettors in favour of electronic fuel injection, which uses sensors to supply fuel to the engine to get the right air and fuel mix. This meant warming up the engine before driving became unnecessary, as modern fuel injection systems provide better management of the fuel system, which makes the car run more smoothly when it’s cold.

So, these days, what’s the best way to warm your engine on cold mornings if idling is no longer necessary in newer vehicles?

“Simply put the key in the ignition and drive. Just give the engine a few seconds to build oil pressure before driving normally.”

2. Your tank might not chew through fuel as fast

Here at RAA, we love saving our members money on fuel. That’s why we asked our motoring expert how much fuel you could waste during unnecessary idling.

RAA Mobility Technology Specialist Mark Borlace estimates that idling an average-sized vehicle for an hour could consume between 1 to 2 litres of fuel. That’s a pretty hefty cost for simply sitting in a running car. And, of course, the bigger the car, the more fuel it will guzzle.

“The vehicle’s emission control systems need to be hot to work properly, so when you spend a long time idling, it doesn’t allow it to get to temperature,” Mr Borlace explains.

“This means untreated, unburnt fuel is going out of the exhaust pipe, which is even worse for vehicles with diesel engines.”

On average, if you reduce the amount of time your car sits idle, you could lower your fuel costs by up to 10%.

3. Mother Nature will thank you

The transport sector is Australia’s second-largest polluter, pumping out almost 20% of the country’s greenhouse gas emissions, according to a Transport Energy/Emission Research report released last year.

The report, led by a duo of researchers from the University of Queensland and Technology Sydney, found running a vehicle’s engine for longer than needed contributes up to 8% of carbon dioxide emissions in Australia. This percentage covers all vehicles, including semi-trailers which were the main idling culprits.

That’s a lot of exhaust fumes circulating through the air and filling our lungs, especially if the vehicle is idling in a poorly ventilated space such as a garage. Even minimal exposure to vehicle pollution can increase the risk of childhood asthma and cause reduced lung function, according to the Transport Energy/Emission Research report.

Some parts of the world are leading the way in doing their bit for the environment by reducing how long vehicles idle. For instance, it’s prohibited to idle in some areas of the UK, while truck and bus drivers in California can be fined if caught idling for more than 5 minutes.

Pre-warming your car can come with other issues

“Another bad habit that can creep in is leaving your vehicle idling unattended in a driveway or garage, which can be dangerous if the area is confined, and fumes build up,” Mr Clark says.

“It’s also not a good idea to leave a vehicle unattended in case there are any faults with the car’s cooling system or radiator.

“You don’t want to return to your vehicle to find that it’s been running with a blown radiator hose and has overheated.”

But, it’s not all bad news. There is an exception to warming up your ride.

“In exceptionally cold climates, such as alpine environments, warming up your ride might be essential if you need some cabin heating or to defrost your windows,” he says.

Final word

The next time you find yourself caught in peak hour or stuck at a red light, don’t worry – your engine won’t likely fail on you. We understand some idling can’t be avoided.

While leaving your engine running for a few minutes before your commute won’t do serious damage, we can’t guarantee the same for your wallet or the environment.