Mercedes-Benz C350 E vs Audi A8

What's the difference?

Plug-in hybrids will probably not appeal to all buyers, but in the premium space they make sense.

Smooth electric driving paired with the potential for weekend trips outside the 100km-or-so range make the C350e a decent thing, let alone its price parity with the C300.

It still doesn’t top the charts for value or practicality, but even aside from the PHEV tech, the C350e remains a fun-to-drive sedan that holds its own in the executive space.

Note: CarsGuide attended this event as a guest of the manufacturer, with meals provided.

The Audi A8 swims in a luxury car shark tank where those paying the big dollars expect top-shelf everything. It delivers a serene driving experience whether you’re in the front or the back, in a superbly engineered and executed luxury sedan package. Not perfect, but very, very impressive.

The C350e doesn’t depart massively from the familiar visual formula that is the current ‘206’ generation C-Class and that’s no bad thing.

Call it conservative if you like, but having seen what’s possible when Mercedes takes risks (hello EQ models), the traditional Mercedes design language is put into healthy perspective. 

Handsome proportions and lines without any fuss - there are no unnecessary creases or panels or materials.

The plug-in C350e comes, as mentioned, with the AMG Line pack, adding 18-inch five-spoke AMG wheels, an AMG front apron, grille insert, and of course EQ Hybrid badging.

The pack also includes AMG Line styling inside, where you’d have to be a Mercedes regular to spot the specifics. The AMG-style steering wheel and seats are the biggest giveaways.

The A8 is close to 5.2 metres long, yet instantly recognisable as an Audi thanks mainly to its evenly weighted proportions, gently curved roofline and overall high-waisted design. Worth noting its drag coefficient (Cd) is an impressively slippery 0.25.

The characteristic look is accentuated by the brand’s signature, six-sided grille, in this instance highlighted by a matrix of high-relief chrome accents. And typically angular LED Matrix headlights sit either side.

Check out our video review for the carefully orchestrated animation they run through when the car is unlocked.

The car looks equally svelte and contemporary from the rear, with just the right amount of chrome lifting the tone and multi-spoke 20-inch rims filling the wheel arches nicely.

As you’d expect, the top-shelf look and feel continues inside with the seats trimmed in aniline leather, perforated on the front and outer rear positions, with genuine hide also covering the centre console, door rails and armrests, steering wheel and upper dashboard.

Fine grain ash wood inserts sit alongside brushed metal elements and a meticulous attention to detail is obvious… everywhere.

For example, the interior door handle design has been thoroughly thought through, requiring a simple underhand tap to open the door, rather than the more conventional, and ergonomically convoluted, ‘over the top’ movement.

Three sleek screens dial up the tech - a 10.1-inch multimedia interface at the top of the centre stack, an 8.6-inch display below it for heating and ventilation, and a 12.3-inch version of Audi’s ‘Virtual Cockpit’ in the instrument binnacle.

And the spacious rear is the epitome of cool, calm Teutonic form and function. You feel relaxed the moment you get in, and isn’t that the primary aim of a car like this?

The space inside the C-Class remains straight-forward as ever. The layout and features don’t stray from convention, meaning there’s a sizable central screen, digital driver display, central cupholders, and places to put things like a phone, with wireless charging included.

The electrically adjustable seat and steering column make getting into a comfortable position easy, and the memory settings keep it that way.

While physical buttons are scarce, the key controls are easy to access via the central multimedia touchscreen and there’s a lack of complicated sub-menus. It's a refreshingly straightforward system compared to some from rivals, especially that of former category benchmark BMW.

There are fewer than a dozen main tile buttons on the menu, and they’re clear and easy to work out. The main screen also defaults to the navigation, and the climate controls are always visible on the touchscreen.

The central storage area is laid out so a phone sitting in the charging pad is slightly hidden, meaning it’s not a distraction, plus the cover means the cupholders and storage can be hidden away. Tidy!

The AMG-style steering wheel’s haptic controls can be used as regular buttons, but more than once on the test drive I nudged the volume and turned my music back on, just a minor annoyance.

In the second row, there’s generous space for a mid-size sedan, and the seats are comfortable for an adult to ride along for a lengthy trip.

There’s a centre armrest, hidden cupholders, and a generally light and open feeling thanks to the panoramic sunroof.

The battery for the hybrid system sits under the second row seats, which means there’s no uneven flooring in the 315L boot.

Space is luxury, be it a large house, a first class seat or a spacious car, and at nearly 5.2 metres long with a close to 3.0m wheelbase the Audi A8 measures up. 

Even before you get in, the doors have an amazing sense of solidity and quality. It’s like opening and closing a bank vault… if that huge circular door had a power-assisted soft-close function. 

There’s copious amounts of space for the driver and front passenger with lots of storage including a lidded box between the front seats, complete with a two-piece longitudinally split top design, so you can sneak your half’s open without displacing your neighbour’s elbow.

The door bins are decent but there isn’t a specific cut-out for bottles, so it’s more a case of laying them down than standing them up. There’s also a handy covered cubby at the end of the door armrests.   

The glove box is a good size and there are two cupholders under a pop-up cover in the centre console.

Of course, the back is where space really counts, and there’s as much room as you’d find in, well… a limo.

Sitting behind the driver’s seat, set for my 183cm position, I enjoyed copious amounts of head, shoulder and legroom. 

There are electric sunblinds for the rear and rear side windows, controlled by buttons in the door as well as the rear seat remote, a 5.7 inch OLED display housed in the beautifully trimmed fold-down centre armrest (which also has a soft close function!). The remote also allows adjustment of the lighting and climate control. Classy.

There’s a shallow storage box and twin cupholders in the armrest, medium size door bins and hard shell pockets on the front seat backs. The rear armrests also feature a small lidded cubby. 

In terms of connectivity and power options there’s wireless Android Auto and Apple CarPlay, a USB-A and USB-C in the front, and an identical pair in the rear, as well as a 12-volt socket in the front and two in the back.

Boot volume is a useful 505 litres (VDA) and the lid is electric, with gesture control. It’s able to easily swallow our three-piece luggage set or the bulky CarsGuide pram. And while the rear seats don’t fold there’s a ski port door to accommodate long items. Just make sure you use the tie-down anchors in the boot to ensure they’re properly secured. There’s a handy netted section behind the left wheel well and a cargo net is included.

Maximum towing capacity, for a braked trailer, is 2.3 tonnes (750kg unbraked) and in more good news, the spare is a space-saver rather than the increasingly prevalent inflator/repair kit.

With an entry price of $202,700, before on-road costs, the A8 is in the thick of it amongst its full-size primo sedan competitors from Europe and Japan. Specifically, BMW’s 740i MHEV ($272,900), the Lexus LS500h ($195,920), Maserati Quattroporte GT ($210,990), Mercedes-Benz S450 ($244,700) and Porsche’s Panamera ($207,800).

By definition, a luxury car should be loaded to the gunwales with features that make life on the road that little bit easier. And aside from the performance and safety tech we’ll cover shortly, the highlights from a very lengthy standard equipment list are - 20-inch alloy rims, metallic paint, adaptive cruise control, digital matrix LED headlights, digital OLED tail-lights, full keyless entry and start, power-assisted door closing, power boot lid (with gesture control), a panoramic sunroof, heated, ventilated and massaging electrically adjustable front seats, heated front armrests and extended leather trim (centre console, door rails and armrests, steering wheel and upper dashboard).

Also included are ambient interior lighting (with 30 colours and six colour profiles), four-zone climate control, electric sunblinds for the rear and rear side windows, ‘Audi Connect’ navigation and multimedia (with voice and handwriting recognition), wireless Android Auto and Apple CarPlay, 17-speaker 730-watt Bang & Olufsen audio (with digital radio) and a colour head-up display.

There’s a lot more, and the A8 can hold its head high in terms of pricing and features relative to its $200K price tag and the competition.

The C350e’s plug-in hybrid drivetrain consists of a 2.0-litre turbo-petrol four-cylinder engine and an electric motor that drives the rear wheels via a nine-speed automatic transmission.

The combustion engine’s peak outputs are 150kW and 320Nm, while the 95kW/440Nm electric motor works with it to land on a total system output of 230kW and 550Nm.

While it’s not lightning quick, the C350e has a decent claimed 0-100km/h sprint of 6.1 seconds, and from the driver’s seat it certainly feels brisk enough to get out of its own way.

The Audi A8 50TDI is powered by a 3.0-litre turbo-diesel V6 engine sending 210kW (from 3500-4000rpm) and 600Nm (from 1750-3250rpm) to all four wheels via an eight-speed automatic transmission (with ‘Tiptronic’ sequential manual shift function) and Audi’s quattro constant all-wheel drive system using a self-locking centre differential.

It also features a 48-volt electrical set-up for mild hybrid functionality built around a belt connected starter/generator, AC to DC converter and a 48-volt lithium-ion battery. 

With energy recovery of up to 12kW from regenerative braking, it enables the A8 to regularly coast with the engine switched off and helps the extended stop-start system to operate smoothly. 

Mercedes officially claims the C350e has a driving range of 104km under NEDC testing, with a 25.4kWh battery supplying the juice.

Official fuel use is just 1.5L/100km, but Mercedes says that becomes 7.6L without any battery charge to help it out.

Under standard 11kW AC charging, it’s about two hours from flat to full, but with the optional 55kW DC fast-charging, it takes about 20 minutes from flat to 80 per cent.

Audi’s official fuel economy number for the combined (ADR 81/02 - urban, extra-urban) cycle is 6.6L/100km, the 3.0-litre turbo-diesel V6 emitting 175g/km of CO2 in the process.

Over a week of city, suburban, and some freeway running we averaged 11.1L/100km, which is acceptable for a 2.1-tonne luxury sedan.

Also worth noting the standard stop-start system works beautifully thanks to the 48-volt starter/generator.

You’ll need 82 litres of diesel to fill the tank and using the official number, that translates to a range of just over 1240km, which drops to around 740km using our real-world figure.

The C350e has a few drive modes that are mostly self-explanatory, those being Battery Hold, Electric, Hybrid, Sport and Individual.

You’ll likely find yourself using Electric and Hybrid most of the time, so we’ll focus on those. Sport is fine but somewhat defeats the purpose of the plug-in system for day-to-day driving.

In electric mode, the C350e doesn’t feel like it’s lacking any power without the engine helping it along. Acceleration is smooth, brisk enough, and a 130km/h top speed means you won’t need the engine on your commute.

Realistically, its 104km range is probably somewhere closer to 80km, but covers you for a decent daily distance.

Let the car use the engine to help out via Hybrid mode and, if you’ve got music playing, you might not notice the engine starting and cutting. The system is smooth and it means a much longer life out of the battery before needing to charge. That, and there’s the benefit of more brisk acceleration thanks to the hefty 230kW/550Nm total outputs.

Everything else about the C350e is classic C-Class - the ride is controlled and the suspension does a decent job of soaking up bumps and rough roads, the comfort and self-levelling suspension makes cornering smooth and inspires confidence.

The most noticeable shortcoming for the car is its transmission hesitation if you put your foot down quickly, though the ability to use the paddles to choose your own gears in Sport mode avoids this.

In Electric or Hybrid, the paddles decide how much braking regen to apply, a useful feature that lets you recuperate some power for the battery if your drive includes a lot of downhill slopes or if you’re avoiding relying on the brake pedal.

The C530e’s extra weight doesn’t dull its driving characteristics as you might expect from a car laden with PHEV tech, so it’s a welcome surprise that you could pick up a plush plug-in for the same price as a combustion C300.

Despite extensive use of aluminium in the ‘ASF’ platform and body panels, the A8 tips the scales at a sturdy 2095kg, yet Audi says the A8 will accelerate from 0-100km/h in just 5.9 seconds. And with 600Nm of peak torque available across a flat plateau from 1750-3250rpm this big four-door gets up and goes hard when asked to. 

At more sedate speeds you’re occasionally reminded there’s a diesel engine under the bonnet, with that characteristic engine and exhaust noise only making their presence felt under pressure. 

In fact, under normal circumstances, noise, be it the engine, tyres or wind is minimal, thanks to a combination of the car’s aero-efficient shape, thick acoustic glass and other sound-deadening measures throughout the car.

The eight-speed auto transmission is suitably smooth, with the central shifter or wheel-mounted paddles able to make snappy sequential ‘manual’ shifts.

There are four drive modes in the ‘Drive Select’ system - ‘Comfort’, ‘Auto’, ‘Dynamic’ and ‘Individual’ - enabling tweaks to the steering, transmission, throttle and suspension. Comfort felt most appropriate most of the time, although dialling up the throttle and transmission to more aggressive modes in Individual adds an enjoyable edge.

The suspension is five-link front and rear with an adaptive air system smoothing even high-frequency bumps and ruts amazingly well.

Push into a corner and the A8 feels nicely balanced, its wide track, sophisticated suspension, plus the quattro AWD system seamlessly distributing drive between the front and rear axles, keeping the big body under control. In fact, you feel the ‘big car shrinking around you’ syndrome from the get-go.

The steering is precise without being overly sharp and road feel is good. Again, with that 2.1-tonne kerb weight in mind, braking is appropriately powerful with big ventilated discs front (350mm) and rear (330mm).

It pays to remember the turning circle is 12.5m, and it’s worth picking your spot for a U- or three-point turn.

Although there’s a lot going on for the driver in terms of screens, buttons and switches it all makes sense ergonomically. The head-up display is helpful and there’s a common sense mix of digital and physical controls, the latter including an audio volume knob. Yes.

Even though the A8 hasn't been assessed by ANCAP, as you might expect, it goes to town when it comes to active safety tech, the car’s standard crash-avoidance features including auto emergency braking (AEB) (pedestrians/cyclists - 5.0-85km/h, vehicles - to 250km/h), ‘Active Lane Assist’, blind-spot monitoring, a reversing camera and 360-degree view (including kerb view function), front and rear parking sensors, ‘Collision Avoidance Assist’ (steering assistance in critical situations), ‘Turn Assist’ (monitors incoming traffic when turning right), and rear cross-traffic alert. 

There’s also ‘Intersection Crossing Assist’, ‘Attention Assist’, tyre-pressure monitoring and an ‘Exit Warning System’ (detects cars and cyclists when opening doors). 

If all that isn’t enough to avoid a crash the airbag count runs to nine, including front and side bags for the driver and front passenger, side airbags covering the outer rear passengers, full length curtains and a front centre airbag to minimise head clash injuries in a side impact. A first aid kit, warning triangle and high visibility vests are also on-board.

There are three top tethers for baby capsules/child seats across the back seat with ISOFIX anchors on the outer positions. 

Mercedes has a five-year, unlimited kilometre warranty which is decent for a premium brand.

Servicing is pricey, though. 

A three-year pack covering a service every 12 months (or 25,000km, whichever comes first) costs $3355, that being just three services.

Four years costs $4630, or five includes a more expensive service and brings the total to $6890. That’s an average of $1378 per service.

Finding somewhere to spend that money shouldn’t be hard as there are 100 dealers listed in Australia.

The A8 is covered by Audi Australia’s five-year/unlimited km warranty, which is now par for the luxury market course, and 24-hour roadside assistance is included for the duration.

Paint defects are also covered for five years, with rust (to the point of perforation) covered for 12. Nice.

Service is required every 12 months or 15,000km with a five-year capped-price plan for the A8 coming in at $3830, or $766 per year. That’s a fair wedge but not outrageous for the category.