Audi A3 vs Audi A4: used car comparison

Published: 7 September 2023

The Audi A3 and Audi A4 are two of the German brand’s most popular models. One’s bigger than the other, but is that the only difference? Each car has pros and cons and in this guide we’ll compare them to help you decide which is right for you.

We’re focusing on the latest versions of each car. The current A3 (available as either a five-door hatchback or a four-door saloon) has been sold new since 2020. The current A4 (available as a four-door saloon or a five-door estate called A4 Avant) was introduced in 2015 and updated in 2019.

There’s a big difference in size between the A3 and the A4 – the A4 Saloon is more than 40cm longer than the A3 Sportback, although the gap between the A3 Saloon and the A4 is smaller at around 26cm.

There’s also a difference in age. The A4 was introduced in 2015 and, even with its refresh in 2019, it’s getting on in years compared with the A3, introduced in 2020. The A4 is still a very comfortable, well-made car, but the A3 feels more modern in terms of its design, engineering and technology.

You’ll find each car is available in more or less the same trim levels. These include the cost-effective Technik model through to the sporty S line and up to the top-of-the-range Vorsprung.

You can also get high-performance versions of each car – there are powerful S3 and S4 models that have an even sportier look than S line models and RS3 and RS4 models that are quite different to any other A3 or A4 models, with even more aggressive design tweaks and sports car-like acceleration.

The A3 and A4 look completely different on the inside. The A3’s dashboard feels very modern and cutting-edge, with a touchscreen infotainment system in the centre and an angular, high-tech look.

The A4’s interior design looks a little more old-school, with a smaller screen perched on top of the dashboard and a less futuristic look overall. However, it’s easier to learn your way around the A4’s various features and systems and its interior has an even more high-quality feel than the A3’s.

Both cars have similar tech, including an infotainment system with built-in sat nav that also supports Apple CarPlay and Android Auto. The A3’s system is controlled with the touchscreen, while the A4 has a little ‘click wheel’ by the gear lever that you use to navigate around the menus. Both systems are easy enough to use, though the A3’s system can be a little slow to load when you start the car.

Other features included as standard are air con, cruise control, parking sensors and a digital driver’s display that you can configure to show whatever information you want.

Most A3 hatchbacks have 380 litres of boot space (plug-in hybrid and four-wheel-drive models have slightly less), while the saloon has 425 litres of space. However, the saloon’s boot has a smaller opening than the Sportback’s, which makes it tricky to load in anything particularly big. Its back seat doesn’t fold down, either.

For context, 380 litres is about average for a car of this size – it’s the same as the boot in a Volkswagen Golf and five litres more than the boot in a Ford Focus hatchback.

The A4 Saloon also has a relatively small boot opening, but its 480-litre capacity is usefully large. The space is flat and square, so loading in things like large suitcases is easy enough. It also has back seats that fold down if you need to load in longer stuff. If you regularly carry large loads, the A4 Avant estate is your best bet. Its 495-litre boot isn’t huge in the grand scheme of things  but it is by far the most practical option among the cars we’re considering here.

Both cars have a very generous amount of space in the front seats. Both also have enough room in the back for two tallish adults to sit comfortably, although passengers can stretch out more in the bigger A4, which also has a middle back seat that’s just about adult-size, at least for short journeys. If you’re looking for a family car, both A3 and A4 work perfectly well, but older kids will have more room in the A4.

• Audi SUV models – a buyer's guide

• Audi A4 vs Audi A5: used car comparison

• Top 10 best used SUVs

The A3 is a really solid all-rounder that feels at home on just about any kind of road. It’s a convenient size for nipping around town and light steering makes it a doddle to park. It feels nimble on winding country roads and solid on motorways. Note that models with 150bhp or more have different rear suspension that makes them feel more agile in corners and gives you a smoother ride.

The A4 doesn’t feel as sprightly as the A3, but then it is a bigger, heavier car. Having said that, it still provides a satisfying driving experience. The steering takes the car exactly where you point it, there’s little lean in corners and it’s a very quiet and comfortable motorway cruiser.

Both cars are available with four-wheel drive (which Audi calls Quattro), giving you a feeling of real security when driving on wet, slippery roads. You’ll find lots of used  A3 and A4 models with a manual gearbox, although automatics are more popular.

There’s a huge selection of petrol and diesel engines to choose from in both the A3 and the A4; the A3 is also available with plug-in hybrid power. All are smooth and quiet and even the least-powerful options give relatively sprightly acceleration.

The A3 costs a bit less to run than the A4. There’s not much difference in fuel economy: Wth a petrol engine, the A3 averages 37mpg to 55mpg and A4s can give 35mpg to 46mpg. Switch to diesel and the A3 can rise as high as 65mpg and the A4 60mpg, according to official figures.

The plug-in hybrid A3 is the most efficient option, with an official average of 256mpg. It also has a usefully long electric-only range of around 40 miles.

There’s not too much car tax to pay for most A3 and A4 models, and rates are particularly low for plug-in hybrid A3s.

Both the A3 and the A4 were awarded full five-star safety ratings by the safety organisation Euro NCAP. Driver-safety features fitted to both cars include automatic emergency braking and cruise control with a speed limiter. The A3 also has lane-departure warning and lane-keeping assist systems.

Audi ranked 22nd among 24 car manufacturers in the J.D. Power 2019 UK Vehicle Dependability Study – not a good showing, despite Audi’s image as a high-quality brand.

Audi A3

Length: 4343mm

Width: 1984mm (including door mirrors)

Height: 1430mm

Boot space: 380 litres

Audi A4

Length: 4762mm

Width: 2022mm (including door mirrors)

Height: 1428mm

Boot space: 480 litres

Both the A3 and the A4 are really good cars. They look and feel upmarket, are good to drive and are practical and fuel-efficient. Buy either one and you’ll enjoy a car that’s very satisfying to own.

We do have to declare a winner though, and that’s the A3. It’s spacious and practical enough for most people’s day-to-day needs and it looks and feels more up-to-date than the A4. It’s also more efficient, more rewarding to drive and costs less to buy.

You’ll find lots of used cars for sale at Cazoo, all available to buy through our trusted dealers.

Cazoo makes selling a car just as easy – just enter a few details for an instant online valuation. If you accept the offer our partners will get in touch to arrange payment and collection of your car at a time that suits you.