Bentley Bentayga vs Mercedes-Benz E400

What's the difference?

The Bentley Bentayga Azure may look a bit awkward and it surely isn't great value for money, but it is a true Bentley and a very good family SUV that not only provides terrific practicality but superb performance and comfort.

A convertible that doesn't feel like one when the roof is in place is no easy task to build, but it's one Merc's engineers have pulled off with the E400 4Matic Cabriolet. Effortless power, a tonne of technology and a comfy, leather-wrapped cabin all make Merc's drop-top E-Class a strong proposition.

You'd think of all automotive brands Bentley, with its beautiful swooping and powerful saloons, would be able to floor us with something just exquisite in SUV form. But right from the 2012 concept the Bentayga has struggled to stun the world with its design.

So, while there are Bentley family traits all over the Bentayga, from the intricate headlights and mesh grille, to the oval tail-lights and body which squats over the rear wheels, the overall design looks awkward to my eyes.

To me it appears the boxy design with the tall, flat roofline and elevated ride height favours practicality over the sleekness possessed by a lower, more coupe-like SUV.

I favour dark coloured clothes because it hides my shapes, creases and bulges, but these are the things you want to see in a car and our Bentley's 'Onyx Black' paint, despite being a beautiful colour with a blue hue added, make it a featureless blob in the sunlight.

A lighter shade or something outlandish like a turquoise or yellow would look amazing, and even better, upset your neighbours.

Let's look at the interior design which is lavish with all the quilted leather and Mulliner customisation, but lacks the modern look of many contemporary cabins with its smallish media screen and busy mosaic of buttons.

I like the little chrome plungers for the air vents, the winged styling to the dashboard and the stitched leather upholstery, but it's easy to spot parts that are shared by other members of the Volkswagen Group (which owns Bentley).

For example, there are the indicator and wiper stalks, as well as the steering wheel buttons, all from Audi. Surely Bentley should have its own crafted parts?

The interior colour scheme on our Bentayga is 'Beluga' (black) and 'Camel' (tan) and the Mulliner option split the colours with a cream tone.

From a family perspective the tan and black will hide dirt, although the cream will struggle. It's possibly the best leather on the planet, however, coming from cattle living high enough that their hides are unblemished by insect stings.

Elegance. That's the word that springs to mind when you first clamp eyes on the E400 Cabriolet. While the Coupe version has a crouched-over sportiness about its exterior design, the convertible is all about big and boat-like proportions, especially with the fabric roof opened.

Like nearly all drop-tops, the E400 looks best with the cabin open to the elements, and the side profile especially paints a picture of well-heeled wafting, with only the AMG alloys and body styling hinting at the performance on offer under the bonnet.

Inside, expect perfectly executed modern luxury, with soft leather seats, touchpoints that melt under the fingers and a sprinkling of woodgrain trim. All of which feel like old-world luxury, nicely juxtaposed by the huge twin-screen display that dominates the dash.

Being shaped like a bus does nothing for the Bentayga's beauty but makes it spacious for cargo and roomy for people.

With its large doors and elevated ride height (the car can be lowered for easier access) it's great for families.

Our Bentayga is a five-seater, which is fine for my little family of four, but there are four- and seven-seat configurations available, too.

Second row legroom is exceptional, even for me at 189cm tall, and sitting behind my own driving position there's still plenty of room.

Headroom is also outstanding throughout. We could be a family that loves top hats, on our way to the top hat championships, and not have to remove our top hats. That's how good headroom and hat room is.

Sun blinds in the second row are vital in Australia, and the electric ones in the Bentayga raise and lower quickly, not just offering protection but also more privacy.

Storage is good throughout with big door pockets and five cupholders.

It seems the cabin space eats into the cargo area because the boot isn't overly large at 484 litres with all seats in place.

Buttons in the cargo area allow the rear of the car to be raised and lowered to make it easier to hoist items in the boot.

For devices there's a wireless phone charger up front along with USB ports in both rows.

It's a two-door, four-seat convertible, so practicality isn't at the very top of its list of strengths.

That said, life is peachy for upfront riders, both of whom will travel in spacious luxury. There are two cupholders hidden beneath a woodgrain cover underneath the climate controls - also home to a power outlet - as well as a clever double-hinged central storage bin that can be opened by either the passenger or driver, and which opens to reveal two USB points.

There's room in the doors for bottles, too, and the entertainment system can be controlled via a touchpad controller mounted above the traditional click wheel - although, to be honest, using it is harder and more time consuming than simply pretending it doesn't exist.

Climbing into the back (and we mean climb - there are no rear doors) is made easier by the fact you can fold and slide the front seats automatically by pulling a lever mounted near the headrest. Once there, though, you'll find space is a little tighter, and you feel weirdly cocooned, owing to the huge raised tunnel that runs through the middle of the cabin, and the low roof line.

There are two cupholders that live in the space where the middle seat would normally go, and there's a little bottle-holder cubby to the left of both backseat riders. There are air vents back there, too, but no temperature controls.

The front doors are huge and really very heavy, requiring considerable heft to open them.

The boot space is predictably a little limited, with 385 litres on offer. There's also a little flip-down separator, which shows you how much room the roof will need to come down, reducing boot space to 310 litres. Speaking of which, the soft-top can be lowered in just 20 seconds, and at speeds up to 50km/h.

One practicality quirk, though. The front (and only) doors are huge and really very heavy, requiring considerable heft to open them, especially if you're parked on a slight angle. Honestly, I was reduced to kind of pushing them open with my foot at times.

At $157,400, the Cabriolet is the most expensive model in the E400 family, and is roughly $20k more than the sedan and $10k more than the coupe variants.

That money buys you a comprehensively kitted-out ride - as it really should - with the E400 Cabriolet arriving with 20-inch AMG alloys, LED headlights (made up of 84 LEDs) with high-beam assist, proximity unlocking with push-button start, air suspension and Merc's AIRCAP - a lip above the windscreen that's designed to push air up and over the cabin when the roof is down.

Inside, you'll find leather seats, dual-zone climate control and the clever 'AirScarf' system, which pumps hot air onto your neck when the roof is down (and it's cold out). You'll also nab heated front seats, power windows front and back and an automatic belt feeder, which saves you reaching over your shoulder to get to your seatbelt. So exhausting.

On the tech front, expect a killer 590W, 13-speaker Burmester stereo, controlled by the seriously impressive widescreen cockpit; two 12.3-inch screens that spill from about the centre of the dash all the way to the driver's binnacle, and control everything from navigation to Apple CarPlay and Android Auto.

There's a whole bunch of safety stuff, including semi-autonomous technology, but we'll drill down on that under the Safety sub-heading.

When Bentley stopped putting its W12 into the Bentayga this year I was unsurprised yet sad. The world is moving toward tighter fuel emissions but the twin-turbo petrol V8 in this Azure is still a beast.

The 4.0-litre turbo-petrol V8 is from the Audi family and I love it as much for its plentiful torque and superb acceleration as the deep rumble of its exhaust.

Making 404kW and 770Nm the V8 can lift and throw the 2.5-tonne Bentayga to 100km/h from a standstill in 4.5 seconds and onto a top speed of 290km/h. I reckon you could get it to 300km/h with the wind behind you.

Drive goes to all four wheels via an eight-speed transmission and a Torsen-type centre differential.

Default drive balance is 40/60 front to rear, with up to 70 per cent of power able to be sent to the front wheels and up to 85 per cent to the rear axle.

I don't think you'll be astounded to hear this powertrain uses a lot of fuel? Let's go there...

It's a fabulous engine, this twin-turbocharged V6 - even if it doesn't feel quite so lively in Cabriolet form as it does in the hardtop equivalents.

The 3.0-litre unit produces 245kW/480Nm, sending it to all four wheels via a nine-speed automatic transmission, linked to the standard 4Matic all-wheel drive system.

Bentley says the Bentayga Azure with the V8 petrol engine will use an average of 11.4L/100km over a combination of open and urban roads.

But what happens if you live in the suburbs not far from the city and drive the Azure every day to do the school drop offs and trips to the shops and then take in some fun country roads? You use an average of 22.8L/100km according to the car's trip computer.

This is still not as high as I was expecting. I've driven V6-powered SUVs which use more than this under the same conditions.

That said, even when using as much fuel as Bentley says you should, an 85-litre fuel tank is only going to deliver an approximate 745km driving range.

Mercedes claims 7.4L/100km on the combined cycle (but you can expect to be pushing nine litres in real-world conditions), with emissions pegged at 170g per kilometre of CO2.

The 66-litre tank will only accepts 95RON fuel.

There are few cars on the road as overloaded with safety technology as the E400 Cabriolet.

The standard stuff is all there, of course. There's a 360-degree parking camera, as well as nine airbags (dual front, dual pelvic/thorax for front-seat passengers, dual sidebags for rear passengers, dual head bags in the doors and a knee airbag for the driver), rollover protection and tyre-pressure monitoring, as well as braking and traction aids.

But the E400 adds some really clever technology, including Merc's Driving Assistance Package Plus, which adds active lane keeping, blind-spot assist, cross-traffic alert and evasive steering assist.

It's this suite of systems that allows the E400 to navigate freeways autonomously, including changing lanes on demand. At the moment, the system will warn you to keep your hands on the wheel every so often, but you can sense a time when that will no longer be required. And that time is soon.

The E-Class range scored the maximum five-star ANCAP safety rating when crash tested in 2016.

The Bentayga is covered by Bentley's three-year/unlimited-kilometre warranty. Servicing is recommended every 12 months or 16,000km.

The good news is all new Bentley's have five years regular servicing included in the cost of the vehicle.

Expect the usual three-year, unlimited-kilometre warranty, with service intervals pegged at 12 months or 25,000km. Mercedes' capped-price servicing scheme limits maintenance costs to $2280 for the first three years of ownership.