If you're weighing up an Audi A5 against an A6, you've narrowed it down to two of the best-looking executive cars Audi makes — but they're aimed at very different drivers. I sell used Audi parts day in, day out, so I see both cars in every state of life, and I get asked this question a lot. Here's the honest version: the A5 is the sleek, sporty one built off Audi's compact executive platform, and the A6 is the bigger, plusher full-size executive. Pick the wrong one and you'll either feel cramped or feel like you've paid for space you never use.
Let me walk you through the real differences so you buy with your eyes open.
Looking for this part? Tell me your Audi model and reg and I'll get you a quote — quality tested used parts with nationwide UK delivery.
What each car actually is
The Audi A5 is a style-led compact executive. For years it came in three flavours — a two-door Coupe, a four-door Sportback (a coupe-shaped hatchback) and a soft-top Cabriolet. It shares its mechanical bones with the A4, so it drives like a sharp, lower-slung A4 with prettier sheet metal. From the 2024 facelift onward Audi confusingly renamed the A4 range as the A5 Sportback and Avant, but the cars most UK buyers shop secondhand are the 2017–2024 Coupe, Sportback and Cabriolet — that's what I'll focus on here. If you're torn between the A5 and its closest sibling, my A4 vs A5 comparison digs into that pairing in more detail.
The Audi A6 is a full-size executive saloon, also sold as the spacious Avant estate. It's a class up — longer, wider, roomier and quieter — built to eat motorway miles in comfort. Think company-car-and-airport-runs rather than back-road blasts.
The quick gut check
- Want something that looks special and feels agile? A5.
- Need genuine rear-seat and boot space for family or business life? A6.
- Want a convertible? Only the A5 offers one.
Size and practicality
This is where the gap really shows. The A5 Sportback measures around 4.75m long and sits low — Parkers and Auto Express both note that the swooping roofline eats into rear headroom, so tall adults in the back will feel it on longer trips. It's a fantastic four-seater for two adults plus occasional rear passengers, but it isn't a natural family hauler.
The A6 is close to five metres long and a class wider, with noticeably more rear leg, head and shoulder room. If you regularly carry three across the back or fit child seats, the A6 is simply the more relaxed car to live with.
What we see on these
Across the two, the A6 generates the most enquiries for the bigger, pricier items — engines, gearboxes and the chunkier body panels that come with a full-size executive. A5 owners tend to ask us for the things that get tired on a sportier, lower car: front-end panels, headlights and the suspension and trim bits. Either way, electrical and infotainment parts come up far more often than people expect on both models.
Boot space
The A5 holds its own thanks to that clever Sportback hatch:
- A5 Sportback: 480 litres (up to 1,300 with seats down) — the practical pick
- A5 Coupe: 450–465 litres, but a small boot opening
- A5 Cabriolet: 370 litres (less with the roof down)
- A6 Saloon: 530 litres
- A6 Avant estate: 565 litres and a far more usable square load bay
On paper the Sportback isn't far off the A6 Saloon, but the A6 Avant is in a different league for bikes, buggies and big shops.
Engines and how they drive
Both ranges lean on Audi's familiar 2.0-litre TFSI petrol and TDI diesel units. In the A5 you'll typically find 35, 40 and 45 TFSI petrols (the 45 making around 245hp and genuinely quick) plus 35 and 40 TDI diesels that are the long-distance champions. The hot S5 uses a 3.0-litre making over 350hp if you want real pace — if that side of the range tempts you, my A5 vs S5 performance and reliability guide is worth a read before you commit.
Used Audi A5 & A6 engines
Tested 2.0 TFSI petrol and TDI diesel units for both ranges, checked before they leave us. A major repair doesn't have to mean main-dealer money.
The A6 offers the same core engines with mild-hybrid assistance, stepping up to a smooth 55 TFSI petrol and, importantly, a 50 TFSIe plug-in hybrid — handy for company-car tax. The A6 is tuned for hushed, effortless cruising rather than sharp responses. If you love the way a car turns in, the lighter, lower A5 is the more engaging steer. If you want to arrive fresh after 200 motorway miles, the A6 wins.
Whichever engine you end up with, when something wears out I keep tested used used Audi engines for both ranges, so a major repair doesn't have to mean main-dealer money. The same goes for the transmission — gearbox faults are one of the bigger bills you can face on either car.
Used Audi A5 & A6 gearboxes
Manual, S tronic and Tiptronic units pulled from low-mileage cars and tested. We match the right code to your model and engine before dispatch.
Running costs and reliability
Diesels are the economy stars in both cars. A 2.0 TDI A5 will realistically return roughly 50–58mpg in steady UK driving, and A6 diesel owners often report comfortably over 50mpg too. Petrols sit lower, generally in the high-30s to mid-40s depending on engine and driving style. The plug-in A6 TFSIe can post big official figures but only if you actually charge it.
On reliability, both share Audi's strengths and weaknesses. The good news is the mechanicals are well-proven. The recurring gripe — confirmed by Honest John owner reviews and What Car's reliability surveys — is electrical and infotainment niggles: flickering MMI screens, phone-pairing trouble and the odd sensor fault. The A6 Avant scored poorly in What Car's 2023 survey but bounced back strongly by 2025, so condition and service history matter more than the badge. Servicing costs sit alongside BMW and Mercedes — in other words, premium. Budgeting for the occasional electrical fix is wise on either car, and it's exactly the sort of part I can supply used at a fraction of dealer prices.
Used A5 & A6 headlights & electrics
Genuine xenon, LED and Matrix headlight units plus the electrical bits that fail, all tested. A used unit saves you a fortune over the main dealer.
A5 vs A6 at a glance
| Audi A5 | Audi A6 | |
|---|---|---|
| Body styles | Coupe, Sportback, Cabriolet | Saloon, Avant estate |
| Size | Compact executive (~4.75m, low roof) | Full-size executive (~5.0m, roomier) |
| Boot | 370–480 litres | 530 (Saloon) / 565 (Avant) |
| Engines | 2.0 TFSI petrol, TDI diesel, S5 3.0 | 2.0/3.0 TFSI, TDI, 50 TFSIe PHEV |
| Typical used price | ~£12,000–£35,000 | ~£14,000–£40,000+ |
| Best for | Style, driving feel, a convertible option | Space, comfort, long-distance refinement |
So which should you buy?
Choose the A5 if looks and driving enjoyment top your list, you mostly carry one or two people, and you fancy something that stands out on the driveway — the Sportback is the sweet spot for blending style with usable practicality, and it's closely related to the Audi A4 parts family, so spares are plentiful. Go for the A6 if you need proper rear space, a bigger boot, the option of an estate or plug-in hybrid, and the calmest possible motorway manners.
Neither is a wrong answer — they're just answers to different questions. Decide how you'll actually use the car 90% of the time, and the choice usually makes itself.
If the more practical saloon is also on your shortlist, my Audi A4 vs A6 guide shows how those two stack up.
Looking for this part? Tell me your Audi model and reg and I'll get you a quote — quality tested used parts with nationwide UK delivery.
Whichever you land on, keeping a used Audi on the road is far cheaper when you fit quality tested used parts. I stock Audi A5 spares and a full range of A6 components, all checked before they leave us, with nationwide UK delivery — so get in touch whenever you need a part.
Sources
- A5 body styles (Coupe, Sportback, Cabriolet) and the 2024+ A4-to-A5 renaming — parkers.co.uk and autoexpress.co.uk
- Boot capacities — A5 Sportback 480 litres, Coupe ~450–465, Cabriolet 370; A6 Saloon 530, Avant 565 — parkers.co.uk and cinch.co.uk
- Engine line-ups — A5 35/40/45 TFSI and TDI plus S5 3.0; A6 55 TFSI and 50 TFSIe plug-in hybrid with mild-hybrid tech — cinch.co.uk and parkers.co.uk
- Real-world diesel economy of roughly 50–58mpg — parkers.co.uk and honestjohn.co.uk
- Electrical/infotainment faults, the A6 Avant's 2023-to-2025 reliability turnaround and premium servicing costs — honestjohn.co.uk and whatcar.com
