If you’re a high-mileage driver, a 2.0-litre engine will usually provide enough power to cruise at motorway speeds without drinking too much fuel. Smaller engines typically prove more efficient when pottering around town while larger, turbocharged units will boast that extra grunt you’ll need for towing heavy trailers.
What size engine do I need?
This will depend on what you plan to use your car for. A giant supercharged V8 engine might be perfect for trackdays but it’ll drink far too much fuel on the school run to make for a sensible family-car engine. In contrast, a supermini powered by an efficient 1.0-litre unit could cost pennies to run but it’ll be useless if you plan to tow a heavy trailer.
Picking the perfect engine will also depend on the type of car you’re after. A compact city car could feel surprisingly nippy with a tiny 1.0-litre engine while a larger SUV will need a significantly bigger unit to keep up with fast moving traffic. Generally speaking, most 1.4-litre turbocharged petrol engines are more than enough to move a Volkswagen Golf-sized hatchback with four passengers and luggage, while 2.0-litre diesels are usually a great choice for anything from a hatchback to a large SUV, such as an Audi Q5.
The next common size engine is a 3.0-litre diesel engine. These larger units typically feel smoother than 2.0-litre engines and are noticeably faster thanks to extra torque. This also helps make them great engines for tow cars. They’re often an option in premium German saloons and SUVs such as the Audi Q7 and Mercedes E-Class.
Let’s investigate different use cases in more detail.
The school run and inner-city commutes
If you mainly use your car for dropping the kids at school or popping to the shops, almost any engine up to 1.4 litres in capacity will do just fine. Smaller engines will usually use less fuel over short journeys or in heavy stop/start traffic.
Longer motorway journeys
If you spend most of your time behind the wheel storming up and down motorways, a larger unit will be more suitable. Engines ranging from 1.4 to 2.0 litres will often feel quieter and more refined at higher speeds and their extra punch will help when overtaking, too – especially compared to 1.0-litre engines.
Picking a larger engine doesn’t necessarily mean you’ll use more fuel. Smaller units often have to work hard to keep up a steady motorway cruise and may prove less economical than a larger, less strained engine as a result.
Towing heavy trailers
Towing large trailers will often require a much more powerful engine with greater torque. Large diesel units often excel in this regard. Four, six or even eight-cylinder engines with a capacity greater than 2.0 litres should prove more than capable of pulling heavily laden trailers – providing you don’t exceed the manufacturer’s recommended towing limits.
Does turbocharging make a difference?
Turbocharging technology – previously the domain of high-performance sports cars – has helped make many small engines more efficient. In some cases, these high-tech units have proved more powerful than the larger naturally aspirated (non-turbocharged) engines they’ve replaced, too. A decent rule of thumb is that a turbocharged engine will produce approximately the same power as a naturally aspirated unit that’s 50 per cent larger.
Ford’s latest 1.0-litre turbo EcoBoost three-cylinder has proved potent enough to replace the firm’s old 1.6-litre non-turbocharged four-cylinder engine. Mercedes has joined the downsizing bandwagon, too – ditching the 6.3-litre V8 from some AMG models in favour of a more compact 4.0-litre twin-turbo unit.
What if I want to go really, really fast…
Some lightweight sports cars don’t need a large engine to deliver face-melting performance – a 2.0-litre Caterham 7 can accelerate from 0-62mph faster than a Ford Mustang with a 5.0-litre V8. For some drivers, however, the effortless pulling power of a huge engine is often just too tempting to pass up.
Save money on your next car
If you’ve picked the perfect new car, and know which engine you want, check out the latest offers on our new car deals page. Still not sure what to buy? Head over to our car chooser tool for help making a decision.