Trying to choose between an Audi A3 and an Audi A4 can feel a bit like being asked to pick your favourite dessert – they’re both brilliant choices, but one might just hit the spot better than the other. Both cars offer that premium Audi feel, smart tech, and a great drive. So, how do you decide?

We’re here to help you untangle the differences. Think of us as your friendly co-pilot, guiding you through the key points so you can find the perfect used Audi for your life. We'll look at everything from size and style to how much fun they are to drive and what they might cost you to run.

What are the key differences?

Size and Styling

The most obvious difference when you see an A3 and A4 side-by-side is their size. The A4 Saloon is noticeably longer than the A3 Sportback (a hatchback), giving it a more commanding presence on the road. If you compare saloon to saloon, the A4 is still the bigger sibling, but the gap isn't quite as large.

While the current A4 has been around since 2015 (with a refresh in 2019), the latest A3 model was introduced in 2020. This gives the A3 a slightly more modern edge in its design and tech, with sharper lines and a more contemporary feel. The A4, however, has a classic, executive look that never goes out of style. It’s all down to personal taste – do you prefer the latest trend or a timeless classic?

Interior and Tech

Step inside, and the age difference becomes a little more apparent. The A3 features a slick, cutting-edge dashboard with a touchscreen infotainment system that’s beautifully integrated. It feels very high-tech and modern. The A4’s interior is just as luxurious and well-built, but its design is more traditional, with a screen that sits on top of the dashboard rather than being built-in.

Don't worry, you won't be missing out on key features either way. Both cars typically come with essentials like built-in sat nav, Apple CarPlay, and Android Auto. The main difference is how you control them. The A3 uses its touchscreen, while the A4 has a handy click wheel near the gear lever. Both are easy to use, though some find the A4's wheel less distracting on the move.

You can also expect to find features like air conditioning, cruise control, and parking sensors in both models. A real highlight is Audi’s Virtual Cockpit – a digital driver’s display that you can customise to show maps, music, or driving data right in your line of sight.

Practicality and Space

This is where your lifestyle really comes into play. If you need plenty of room, the A4 starts to pull ahead. Most A3 hatchbacks offer 380 litres of boot space, which is perfectly fine for the weekly shop or a weekend away. The A3 Saloon bumps this up to 425 litres, but its smaller boot opening can make it tricky to load bulky items.

The A4 Saloon, on the other hand, boasts a generous 480-litre boot that’s flat and square, making it easy to pack. And if you really need to carry a lot, the A4 Avant (the estate version) offers a huge 495 litres.

Both cars have plenty of space up front for the driver and passenger to get comfortable. In the back, two adults can fit without any trouble. However, your rear passengers will thank you for choosing the A4, as it offers more legroom. It’s the more comfortable option for families with older children or if you regularly have adults in the back.

The Driving Experience

So, how do they feel on the road? The Audi A3 is a fantastic all-rounder. It’s nimble and easy to drive around town thanks to its light steering, but it’s also comfortable and composed on the motorway. It handles corners with confidence and feels agile, making it a genuinely fun car to drive on a winding country road.

The A4 is larger and a bit heavier, so it doesn’t feel quite as sprightly as the A3. However, it offers a supremely satisfying and refined driving experience. The steering is precise, it feels incredibly stable through corners, and it’s exceptionally quiet and comfortable on long journeys. If you spend a lot of time on the motorway, the A4 is a fantastic cruiser.

Both models are available with Audi’s famous quattro four-wheel-drive system, which provides extra grip and confidence in slippery conditions.

Running Costs

When it comes to the cost of ownership, the smaller and lighter A3 generally has the advantage. With petrol engines, you can expect the A3 to average between 37-55mpg, while the A4 delivers around 35-46mpg. If you opt for a diesel, the A3 can achieve up to 65mpg, with the A4 not far behind at up to 60mpg.

The real star for efficiency is the plug-in hybrid (PHEV) version of the A3. It has an official average of over 250mpg (though real-world figures depend on how you drive) and can travel for about 40 miles on electric power alone. This makes it a brilliant choice for slashing your fuel bills if you have a short commute and can charge at home.

Safety and Reliability

You can rest easy knowing that both the A3 and A4 are very safe cars. Both received the maximum five-star rating from the safety experts at Euro NCAP. They come equipped with important safety features like automatic emergency braking, which can help prevent a collision. The A3 also often includes lane-departure warning as standard.

Audi is known for its high-quality builds, giving you that solid, premium feel. While no car is perfect, choosing a used car from Cazoo means you get the added peace of mind that comes with a thorough 300-point inspection before it even reaches your driveway.

The Verdict: A3 or A4?

Honestly, you can’t go wrong with either of these cars. They are both superb vehicles that deliver a premium experience.

If we had to pick an overall winner for most people, it would be the Audi A3. It’s spacious enough for daily life, feels more modern inside, is cheaper to buy and run, and offers a wonderfully balanced and rewarding drive.

However, the Audi A4 is the clear choice if space and comfort are your top priorities. If you have a growing family, frequently travel long distances, or just want that extra bit of legroom and boot space, the A4 is an outstanding option that delivers a more luxurious and relaxed experience.

Find your perfect Audi with Cazoo

Deciding is the hard part, but buying should be easy. At Cazoo, you can browse a wide range of high-quality used Audi A3 and Audi A4 models right from your sofa. We show you all the features and highlight any little imperfections upfront, so there are no surprises.

Once you’ve found the one, you can buy or finance it online and have it delivered straight to your door. Plus, with our 7-Day Money-Back Guarantee, you have a whole week to make sure it’s the perfect fit for your life. It’s the simple, worry-free way to get into your next car.