The Audi A6, the BMW 5 Series and the Mercedes E-Class have been the same three-way argument for thirty years, and most comparisons still write it that way: badge, ride, image.
That is no longer the useful question, because the three ranges have stopped offering the same things. One of them has dropped diesel entirely. One has no electric version at all until 2027. And one sells an electric estate, which the other two do not.
Work out which of those matters to you and the decision is largely made before you get to how they drive.
The Short Answer
The Mercedes E-Class if you cover big miles, because it is the only one of the three with a proper diesel choice: a four cylinder, a straight six, and the only diesel plug-in hybrid in the class.
The BMW 5 Series if you want an estate and an electric car at the same time, because the i5 Touring is the only electric estate here and BMW is the only brand offering every bodystyle in every fuel.
The Audi A6 if you want the electric one as a hatchback shape and the best cabin screens, with the caveat that Audi publishes less about its own cars than either rival.
Diesel: the Split Most Comparisons Get Wrong
| Diesel offering | |
|---|---|
| Mercedes E-Class | Three ways. The E 220 d four cylinder at 126g/km and 58.9mpg, the E 450 d straight six at 367hp, and the E 300 de, the only diesel plug-in hybrid in the class |
| Audi A6 | One, the 40 TDI quattro with mild hybrid assistance and 400Nm. Audi does not publish its power output in PS on its own page |
| BMW 5 Series | None. BMW UK's own technical data lists no diesel in either bodystyle |
BMW UK's 5 Series hub still offers a Diesel filter, and its page carries a footnote saying a model is no longer available to order without naming which. A UK franchised dealer was still advertising a new 520d when we checked, which will be a car already built rather than a factory order. If you specifically want a diesel 5 Series, ask us and we will find out what the real position is rather than guess from a website.
For a driver doing 25,000 miles a year this is the single most decisive thing in the comparison, and it is the fact most out-of-date reviews get wrong.
The Electric Versions Are Not the Same Shape
| What the electric version is | |
|---|---|
| BMW | i5 in Saloon and Touring. Same bodyshell as the 5 Series, separate badge. BMW is the only one of the three offering every bodystyle in petrol, plug-in hybrid and electric |
| Audi | A6 e-tron in Sportback and Avant. There is no electric A6 saloon, which catches out anyone cross-shopping against a 5 Series Saloon |
| Mercedes | None. No electric E-Class until 2027. The electric Mercedes in this space is the separate EQE |
So if you want an electric version of this car as a saloon, Audi is out. If you want an electric version at all, Mercedes is out. And if you want an electric estate, BMW is the only answer.
The A6 e-tron is the longest-ranging of them on paper, at up to 463 miles for the Sportback in performance form on a 100kWh battery, charging at up to 270kW. The i5 runs an 81.2kWh battery and up to 382 miles. Both are strong; the Audi is in another bracket on range.
What a Plug-in Hybrid Costs You in Boot Space
| Standard | As a plug-in hybrid | |
|---|---|---|
| Mercedes E-Class Saloon | 540 litres | 370 litres |
| Mercedes E-Class Estate | 615 litres | 460 litres |
| BMW 5 Series Saloon | 520 litres | 520 litres, no penalty |
| BMW 5 Series Touring | 570 to 1,700 litres | 570 to 1,700 litres, no penalty |
| Audi A6 Avant | 503 litres, 1,534 folded | Audi does not publish a figure |
615 litres in a diesel Estate is the most space in this comparison. 370 litres in a plug-in hybrid Saloon is the least, and it is 170 litres less than the same car with a conventional engine. BMW charges nothing at all for the battery, keeping the full 520 litres on the Saloon and the full 570 to 1,700 on the Touring including the electric i5. If you are going plug-in hybrid and you use the boot, that gap is worth more than anything on the spec sheet.
Audi publishes no boot figure on any A6 model page at all, electric or combustion. The Avant figures above come from Audi's own press material rather than from the page where you would choose the car.
What Euro 6e-bis Did, and Who Updated Their Website
Plug-in hybrid CO2 figures have risen sharply because the assumption about how much of your driving is electric was rewritten. The cars did not change. Published figures did, and this comparison shows it more clearly than any spec sheet.
| Then | Now | |
|---|---|---|
| Mercedes E 300 e Saloon | 13 g/km on Mercedes' own December 2024 price list | 47 g/km on the current page |
| Mercedes E 300 de Saloon | 11 g/km | 40 g/km |
| BMW 530e Saloon | 17 to 14 g/km at launch | 58 to 49 g/km |
BMW UK lists the 530e Saloon at 58 to 49 g/km and the 530e Touring at 20 to 16 g/km on the same day, with the Touring quoting 313.9 to 403.5mpg alongside it, which is an old-standard figure that has not been refreshed. The 550e has been updated on both bodies. So if you are comparing two BMWs on CO2 right now, you may be comparing two different test methods. Ask us to confirm the figure for your exact derivative before you use it for anything.
What this does to your tax is not what the headlines suggest. A qualifying plug-in hybrid is treated as emitting 1 g/km for employment taxes, with the benefit-in-kind percentage set by electric range alone, which protects company car drivers and salary sacrifice. It does not cover vehicle excise duty, capital allowances or the corporation tax disallowance on leased cars, which all still use the real figure. We have written about that in full here. Bands and rates change each tax year, so check with your accountant.
Towing, and Who Will Tell You
| Braked | Unbraked | |
|---|---|---|
| Mercedes E-Class | 2,100kg, the highest here, across E 200, E 220 d, E 300 e and E 300 de | 750kg |
| BMW 550e xDrive | 2,000kg | Not published |
| BMW 530e | 1,800kg | Not published |
| BMW i5 | 1,500kg | Not published |
| Audi A6, any version | Not published | Not published |
Mercedes is the only one of the three that publishes both figures, and it also tows the most. BMW publishes braked figures by variant and no unbraked figure. Audi publishes nothing for any A6, electric or combustion, which we checked across five separate first-party documents.
If you tow, that is not a close call. It is one brand that answers the question, one that half answers it, and one that cannot answer it from its own website.
Inside: Three Different Views on Buttons
| Screens | Climate controls | |
|---|---|---|
| Mercedes E-Class | 12.3 inch driver, 14.4 inch centre, and a 12.3 inch passenger display, the largest here | Not published by Mercedes either way, so we are not going to tell you |
| Audi A6 | 11.9 inch driver, 14.5 inch centre curved OLED, and a 10.9 inch passenger display | Entirely on screen. Reviewers report barely any physical buttons in the cabin |
| BMW 5 Series | 12.3 inch driver, 14.9 inch centre, the largest single screen. No passenger display at all | Temperature lives in a permanent on-screen ribbon and in the touch-sensitive Interaction Bar, but the vent direction controls stay physical |
The passenger display is gated by trim on both cars that offer one. On the Audi it is Edition 1 only. On the Mercedes it is absent on the two lowest trims, optional in the middle and standard only at Premium Plus level. So seeing one in a press photograph tells you very little about the car you would be quoted.
Mercedes also has the broadest trim ladder of the three, six against BMW's three and Audi's three, and worth knowing that CO2 climbs with trim on the same engine because of wheels and weight. The E 220 d Saloon runs 124g/km on AMG Line and 134 on Exclusive Premium Plus. For a company car driver the trim choice can move the band.
So Which One?
The E-Class for high mileage, for towing, and for the biggest boot if you avoid the plug-in hybrid. The deepest diesel range in the class by a distance, and the only one that publishes everything you would want to check.
The 5 Series for flexibility. Every bodystyle in every fuel, an electric estate nobody else offers, no boot penalty for choosing the plug-in hybrid, and the only cabin here with any physical climate hardware left.
The A6 for the electric one, where it has the longest range and the fastest charging of the three, and for the cabin if you like the screens. Accept that Audi publishes less about its own cars than either rival, and ask us to confirm anything that matters to you in writing.
Compare the Three Directly
Current lease pricing on each.
Worth Reading First
The guides that cover the tax and the money.
Want All Three Priced on the Same Terms?
Tell us your mileage, whether you tow and whether you need an estate, and we will quote all three on matching terms and confirm the figures each manufacturer will not publish.
Talk to LetsLeaseFrequently Asked Questions
It depends on three things rather than on which badge you prefer. If you cover big miles, the E-Class, because it is the only one with a proper diesel choice. If you want an estate and an electric car at the same time, the BMW, because the i5 Touring is the only electric estate of the three. If you want the longest-range electric one and you like the cabin, the Audi, accepting that it publishes less about itself than either rival.
Not from BMW UK's own range as published. Its technical data pages list no diesel in either bodystyle, though its hub still offers a diesel filter that returns nothing and carries a footnote about a model no longer being orderable without saying which. A franchised dealer was still advertising a new 520d when we checked, which will be a car already built. If you want one, ask us and we will establish the real position rather than guess from a website.
The Mercedes, by a distance, and it offers diesel three ways. The E 220 d is a four cylinder at 126g/km and 58.9mpg, the E 450 d 4MATIC is a 367hp straight six, and the E 300 de is the only diesel plug-in hybrid in the class. Audi offers one diesel, the 40 TDI quattro. BMW offers none.
No. The electric car is the A6 e-tron and it comes as a Sportback, which is a liftback shape, or as an Avant estate. There is no saloon. That catches out anyone cross-shopping it against a BMW i5 Saloon or an E-Class Saloon, because the three are not the same shape once you go electric.
Not yet. An electric E-Class is expected in 2027. Today the electric Mercedes in this part of the market is the EQE, which is a separate model rather than a version of the E-Class. So if you want an electric version of this specific car, Mercedes is the one to rule out.
On the Mercedes, heavily. The E-Class Saloon drops from 540 litres to 370 and the Estate from 615 to 460. On the BMW, not at all: the 530e and 550e Saloons keep the full 520 litres and every Touring including the electric i5 is 570 to 1,700. Audi publishes no boot figure on any A6 page, so you cannot check it on audi.co.uk. If you are going plug-in hybrid and you use the boot, that is worth more than anything on the spec sheet.
The Mercedes, at 2,100kg braked and 750kg unbraked, and the same figures apply across the E 200, E 220 d, E 300 e and E 300 de. BMW publishes 2,000kg for the 550e xDrive, 1,800kg for the 530e and 1,500kg for the i5, but no unbraked figure. Audi publishes no towing capacity for any A6 at all, electric or combustion, which we checked across five separate first-party documents.
Because the assumption about how much of a plug-in hybrid's driving is electric was rewritten, which pushed published figures up sharply without anything changing on the cars. Mercedes' own December 2024 price list had the E 300 e Saloon at 13g/km; its current page says 47. The E 300 de went from 11 to 40. BMW's 530e Saloon was 17 to 14 at launch and is now 58 to 49.
For a qualifying plug-in hybrid, no. Such a car is treated as emitting 1g/km for employment taxes, with the benefit-in-kind percentage set by electric range alone rather than by the CO2 figure. That covers company car benefit-in-kind, salary sacrifice and the fuel benefit charge. What it does not cover is vehicle excise duty, capital allowances and the corporation tax disallowance on leased cars, which all still use the real figure. So the driver is protected and the business is not. Bands and rates change each tax year, so check with your accountant.
The Mercedes has the most glass, with a 12.3 inch driver display, a 14.4 inch centre screen and a 12.3 inch passenger display, the largest passenger screen here. The BMW has the biggest single screen at 14.9 inches and no passenger display at all. The Audi runs an 11.9 and 14.5 inch curved OLED with a 10.9 inch passenger display. Worth knowing the passenger display is gated by trim on both cars that offer one, so a press photograph tells you little about the car you would be quoted.
The BMW is the only one where any physical climate hardware is confirmed: temperature moved into a permanent on-screen ribbon and into the touch-sensitive Interaction Bar, but the vent direction controls remain physical. The Audi has gone furthest the other way, with climate entirely on screen and almost no physical buttons in the cabin. Mercedes does not state either way in its own material, so we are not going to tell you. Sit in all three if this matters to you.
LetsLease is a credit broker rather than the lender. We arrange the agreement and place it with a funder such as Lex Autolease, Novuna, Ayvens or Santander, and that funder owns the vehicle and holds the agreement with you. Because we work across several funders rather than one, we can compare how each prices the same car.