If you've ever driven a classic car, it probably took a little time to get a cold engine going. Today, the debate over whether you need to warm up a vehicle before driving continues.
Are there still benefits to idling while a car heats up? What happens if you don’t let your car warm up? We address these questions and others in our handy guide.
EASY AS HACK
When warming up your car, consider its engine type and its age, and accelerate gently before hitting the road.
At a glance
The time it takes for cars to warm up and reach their optimal operating temperature:
- Older cars require a 2-3 minute warm-up
- Modern vehicles typically take only a few seconds
- Electric and hybrid cars do not require any warm-up time
should you warm up your car before driving?
Most of us don’t fancy getting into a cold car on a winter’s day, we’d rather let it warm up before setting off. But whether you should warm up your vehicle before driving depends on the type of car you have and its age.
Before the early 1990s,[1] cars equipped with carburettors needed time to warm up to lubricate the system. Since then, vehicle manufacturers have replaced the carburettors in petrol and diesel vehicles with fuel-injected engines, which work differently. Electric and hybrid cars warm up far quicker than any car with an internal combustion engine (ICE).
Warming up an old ‘classic’ car
Carburettors power classic cars by sucking air and drawing fuel into the airstream using pressure differences. However, external factors, such as a frosty morning when oil is thicker, can affect performance.[2] It takes time for a cold engine in an old car to reach it’s the right operating temperature, mix the fuel and air, and circulate the oil evenly, allowing the parts to lubricate and move smoothly.
Warming up petrol or diesel cars
Most other cars have a fuel injection system, that deliver fuel with much more precision through a small nozzle under pressure. Computer controls and sensors provide exact amounts of fuel almost instantly, enabling higher performance levels, better fuel economy, and reduced emissions.[2]
The result is that it takes around 30 seconds upon starting for lubrication to happen in more efficient modern engines. Therefore, they don’t need the same amount of warm-up time as cars with carburettors.
Warming up a hybrid car or electric vehicle
EVs and hybrid cars operate efficiently without warming them up before you drive. EVs can preheat their lithium-ion (Li-ion) batteries for maximum efficiency and instantly heat the inside.[3] However, you may want to warm the battery up while it’s charging before driving in icy weather.
how long should you warm up your car for?
The time it takes for cars to warm up before you can drive them depends on the type of vehicle you have – whether it’s an older model, a modern petrol or diesel car, or a hybrid/electric – and of course, on the outside temperature.
- Older ‘classic’ cars: Warm-up takes 2-3 minutes before reaching the correct operating temperature
- Petrol or diesel vehicles typically take just a few seconds to warm up
- Electric and hybrid cars don’t need any warm-up time
No matter what type of car you drive, it’s essential to remember that you only need to let it warm up just long enough for the windshield to clear and defog.
Read our article: How to defrost your car windows and windscreen.
Running a car engine unnecessarily, also known as idling, wastes fuel, increases emissions and contributes to health issues caused by air pollution.
Find out When it’s illegal to leave your engine running in cold weather.
how to warm up your car engine?
Traditional internal combustion engine system (ICEs):
Start by turning on the interior car heater and the fans in colder weather.
Avoid harsh acceleration when you start driving, as the oil won’t have time to lubricate and protect the engine. It could put additional stress on engine parts, leading to wear and tear.
Hybrids and EVs:
Warm the car (precondition it) while plugged into its charger. It uses less battery power than warming up your vehicle while it’s in motion, which reduces the driving range.[4]
Read your car’s manual for the manufacturer’s advice on warming up your specific engine.
A Tesla owner’s manual recommends setting climate conditions 30-45 minutes before hitting the road. The app will notify you when it has reached the preconditioned temperature.[5]
When it’s cold and you’re driving, Leaf suggests using the steering wheel heater as it uses less power than the climate control system.[6]
are there any times you should let your vehicle warm up for longer?
Yes, at the following times, you should let your vehicle warm up for longer:
- In freezing weather, your car may not warm up or start at all, particularly if it’s old. A cold battery produces less power than a warm one, and the oil gets thicker (more viscous) as the temperature drops. So, you may need to warm the car up for a few more minutes.
- When towing heavy loads, even in a modern fuel-injected car, the cold puts additional strain on the engine. Gradually warming it up for a few minutes and driving off gently will help it reach its optimal operating temperature without adding to the stress.
- If temperatures are lower than the optimal for an EV battery (e.g. below 20°C), you should warm it up while plugged in for 5-10 minutes before you plan to leave.[7]
If you don’t warm up the engine in an old car with a carburettor, the oil movement will be sluggish, and you could stall. You also risk increasing engine part wear and tear. Warming up an older car and driving gently, avoiding fast acceleration, will help the engine system work more efficiently and prevent potential damage.
You should still warm up a fuel-injected internal combustion engine to ensure every part is lubricated and to optimise performance. However, you don’t need to spend as much time letting it idle as a classic car.
are there any times you should let your vehicle warm up for longer?
Except from the examples described above, there’s usually no need to warm up your car for long, especially if it’s a modern fuel-injected vehicle.
Minimising the warm-up time can lead to the following benefits:
- Better fuel efficiency, because less idling saves fuel[8], i.e. the engine reaches its optimal temperature on less[9]
- Reduced emissions and lower pollution levels as fewer harmful chemicals are released into the air
- Longer engine life, particularly in an old or classic car.
In freezing weather, you can use the short time it takes to warm up the car to de-ice it and remove any snow.
Discover why many trust Ageas Car Insurance to protect their vehicle.
Sources
[1] Wikipedia - Fuel Injection
[2] YouTube - Carburetor vs Fuel Injection: What Are the Differences?
[3] Octopus Energy - tips for driving an EV in winter
[4] Quora - Does it make sense to warm up a new electric car before driving it?
[5] Tesla - Cold Weather Best Practices
[6] Nissan USA - 2023 LEAF manual
[7] Plugsurfing - Electric cars in winter: How to drive and charge your EV in cold weather
[8] CRC Industries - How to Get Better Gas Mileage
[9] Great State Transmissions - Let Your Engine Warm Up: How it Affects Your Transmission During Summer
