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.