Mercedes-Benz GLC-Class vs Lexus RX450H

What's the difference?

Like I said right from the start, this new, hybrid version of the AMG GLC63 is technically superior to the model it replaces in every meaningful way. It is faster, more powerful and more fuel efficient and therefore a better performance SUV than the model it replaces.

Is it a better model than the one it replaces? Ultimately that will come down to how much stock you put into the soundtrack and your feelings on an AMG not powered by a V8 engine.

Because if you can see past that, then the AMG GLC63 is an absolutely fantastic performance SUV. Not only does the new powertrain make it faster in a straight line, but the chassis is very well-balanced, making for an engaging driving experience.

For those who can look past the smaller engine they will be rewarded with an incredibly fast and rewarding-to-drive member of the AMG family.

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

The RX is a little frustrating - it's going after Mercedes and BMW and Audi in a hotly-contested space and falls over in a couple of key areas. The media/sat nav system is hopelessly outdated and the drivetrain fails to deliver a significant performance or fuel benefit (although, given its 2.2 tonnes, perhaps it delivers a miracle).

It does come with a rock-solid, scandal-free reputation, a reputation for spectacular customer service, it has a lovely cabin and it's certainly an individual looker. For plenty of people, that's quite enough.

The GLC63 is unmistakably an AMG from the moment you first lay eyes on it. That’s thanks to the AMG-specific elements, starting with the grille with vertical strikes and the AMG crest on the bonnet; which is now a signature item for the performance sub-brand.

The GLC63 is also fitted with the Night Package II design kit; this adds a darkened grille and black chrome badging to further enhance its visual appeal.

The AMG-specific alloy wheels and more aggressive stance do mean the GLC63 stands out from the rest of the GLC range, helping it look fast even when it’s standing still.

There's a lot of RX and there's a lot going on in that creased, folded and teased sheetmetal. It's a unique design, with a huge 'spindle grille', big lights and the fast glass both front and rear.

It positively screeches Lexus DNA and was a polarising force on our driveway for the week. Most weren't sure, but knew for certain it was a Lexus.

Aggressively flared wheelarches like this aren't common on SUVs (although the squared-off ones are). It's right up on stilts, but the 20s you find it rolling on help to reduce its visual bulk.

That wacky rear quarter glass reminds me of the BMW i3's but it's a Lexus SUV signature. It's quite striking. Do I like it? Not really, but that's completely subjective. You can tell, though, it's built tight as a drum.

Inside is a bit calmer, beautifully laid-out and built to last. The materials are almost all top notch, with lovely switchgear and the real leather is really nice.

There is absolutely nothing avant-garde in there (apart from maybe the pinstripe effect on the centre console), it's all terribly comfortable and easy on the eye. But not exciting, though not all Lexuses are.

This particular car is very US-centric and, if I may, a particularly sunny and humid part, so it can't be too wacky.

Inside the GLC63 is clearly a derivative of the rest of the range, with its C-Class-inspired design and layout, but there’s enough AMG-specific elements to ensure it looks and feels special. This starts with the AMG steering wheel, which comes not only with a thick rim wrapped in Alcantara, but also some AMG special dials to adjust the various performance settings for the powertrain, suspension and transmission.

Then there are the AMG-specific seats, which look good and offer good support for the driver and front seat passenger. The rear seats offer decent space for what is a mid-size SUV, with room enough for two adults or teenagers or three smaller kids.

Those in the back aren’t particularly well looked after though, with only rear air-con vents and small door pockets but no USB charging ports or other small item storage.

The boot is 590 litres, down from 620L in the rest of the range, thanks to the addition of the rear-mounted electric motor. There’s also no room for the temporary spare the rest of the GLC range gets and instead you have to make do with a puncture repair kit.

There is plenty of room inside this big unit, which is very welcome. Front seat passengers have lots of storage, such as a deep central bin under the armrest, dual cupholders and big door pockets with bottle holders.

Step into the rear and there is a ton of leg and headroom although the transmission tunnel intrudes slightly for the middle passenger. Chuck them out, drop the armrest and you have two more cupholders and each door has pockets and bottle holders.

The boot is pretty big considering the angle of the rear glass. You start with 453 litres (but an expanse of flat floor), which rises to 924 litres with the split-fold seats down. That seems conservative given just how much space you appear to have.

The RX450h F Sport lightens your bank account of $102,460 before on-road costs, the only hybrid SUV within cooee of this price.

That nets you 20-inch alloys, a 15-speaker stereo, dual-zone climate control, heated and cooled electric front seats, reversing camera, that ever rare CD player, keyless entry and start, a solid safety package, reversing sensors, active cruise control, sat nav, a massive sunroof, auto LED headlights, head-up display, partial leather interior, power tailgate, auto wipers and a space-saver spare.

The Lexus media system is run from the gigantic dash-mounted screen that is shamed only by those massive Tesla units.

Sadly, the joystick-style control remains as does the very confusing software system that is less than delightful to use. It's such a shame that a tech-laden machine is let down by the world's most baffling entertainment system.

Once you get it working and understand it, it's okay, I guess, but several years into this job I still can't easily fathom how it works. And that naff analogue clock...

F Sport cars also pick up adaptive suspension and a several driving modes to liven things up.

This is what lies at the heart of the AMG GLC63’s success or failure. As I mentioned at the beginning, the previous generation’s 4.0-litre twin-turbo V8 has been replaced by an F1-inspired plug-in hybrid powertrain.

But don’t think that means AMG is suddenly focused on efficiency over performance. When AMG says the powertrain is inspired by the brand’s success in Formula 1 racing, what it means is the battery and electric motor provides a significant performance boost to support the internal combustion engine, not just save fuel.

To that end the combination of the turbocharged 2.0-litre four-cylinder petrol engine and the rear-mounted electric motor produces an impressive 500kW and 1020Nm. That’s a massive jump over the 375kW/700Nm made by the outgoing V8.

You can choose three different powertrains in the RX - a 3.5-litre V6, a 2.0-litre turbo four-cylinder, or this one, the 3.5-litre V6 with hybrid.

As a series hybrid it can run for short distances on electric only before firing up the V6 to supply charging and motivation.

The 3.5 produces 193kW/335Nm along with the electric motor. That torque figure seems low and it probably is, but that's a function of the weird way of measuring torque from a hybrid unit. The combined power figure, however, is 230kW.

The hybrid system is hooked up to Lexus' CVT auto and sends power to all four wheels. Lexus says the 450h will complete the sprint from 0-100km/h in 7.7 seconds, which isn't bad for a 2210kg SUV.

Mercedes makes no secret that the battery is designed for performance, not saving fuel. It only has a 14km EV range but can recharge quickly on the move to provide a power boost when needed.

But despite all that, the GLC63 is actually significantly more fuel efficient than the old V8, using a claimed 7.3L/100km, which is a massive 4.9L/100km improvement over the old model. Although, on our day-long test drive we didn’t manage to come close to that claimed figure and instead saw returns around 11L/100km, albeit after a lot of spirited open-road driving.

The official combined cycle figure is listed as 5.7L/100km. And, uh, yeah, we didn't get that. I did manage 8.9L/100km over the week, which included a long motorway run from Sydney up to the Blue Mountains (a roughly 160km round trip).

Anyone who still believes in the adage ‘there’s no replacement for displacement’ hasn’t driven a modern turbocharged and hybridised engine. The GLC63 is a demonstration of the metaphorical and literal power of modern technology, combining an extremely efficient and potent internal combustion engine with an electric motor to make enormous real-world performance.

To be blunt, the GLC63 feels like a rocketship out of corners, launching with a ferocity and relentlessness the old V8 simply can’t match. It shouldn’t come as a surprise, a mid-size SUV with 1020Nm was always going to have plenty of performance, but even so it’s a shock to the system every time you give the GLC63 full throttle. Officially AMG claims it takes just 3.5 seconds to run 0-100km/h and has an electronically limited top speed of 275km/h - mighty impressive figures for a five-seat mid-size SUV.

To help get all that torque to the road, AMG deploys torque distribution technology that allows for it to be split an even 50/50 front/rear all the way to 100 per cent to the rear tyres.

Other technologies deployed to enhance its handling include AMG Ride Control suspension with adaptive damping and rear-axle steering. There’s also eight AMG Dynamic Select driving modes and four AMG Dynamics settings (Basic, Advanced, Pro and Master), so it’s a complex vehicle that is designed for the enthusiast.

While it’s easy to drive around town, once you get out on the open road you can really get a sense of the GLC63’s performance potential. Beyond just its powertrain the suspension offers good body control and the rear-axle steering helps it feel agile and responsive. 

It’s not perfect though. At times the complexity of the system does lead to some hesitation when you put your foot down. It certainly lacks the linear power delivery of the old V8 and makes for a slightly trickier driving experience at times.

As for the sound, which is one of the biggest elements missing from the V8, Mercedes has added AMG Real Performance Sound, which features a pressure sensor in the exhaust that picks up on the engine note and plays it through the speaker system. It certainly helps make for a louder, more noticeable engine noise, but it still sounds more like an A45 than the previous GLC63 and for many would-be buyers, that’s a major turn-off.

Right. So this is a salutary lesson about tyre pressures. The first few days the tyres were only pumped up to 200kpa (29psi). That's an easy 100kpa (14psi) short of the required 300 (43psi).

Every time I, or my wife, went around a corner, the big Dunlop Sport Maxx SPs would squeal and squirm and it was most unsatisfactory.

So check your tyres, because the extra 100kpa makes all the difference. Also, the number of service stations it took to find a working pump was unacceptable. Pull your socks up, Sydney.

Anyway.

Correct tyre pressures enacted, the big Lexus turned into a comfortable, competent cruiser. Its motorway performance is super-impressive, purring along the M4 and it's ridiculously poor surface like it was born to it. Which it sort of was.

The hybrid drivetrain allied to the CVT is mostly whisper quiet. It's not the most responsive combination, the initial step-off of the electric motor's torque soon giving way to the rubber band effect of the transmission.

It doesn't feel as swift as the claimed 7.7 seconds and it would be nice if the drive select dial made a genuine difference to the throttle and transmission's response.

In the city, it's a proper wafter, moving about the broken down city streets of Sydney without fuss and a plush ride that's a bit of a surprise given the huge wheels and substantial weight of RX.

It's all very easy and pleasant but the wild looks do not match the experience. Which is not a criticism, just an observation.

The RX ships with eight airbags (including knee airbags for both front seats), ABS, stability and traction controls, blind spot sensor, reversing camera, forward collision warning, forward AEB and reverse cross traffic alert.

There are three top tether restraints and two ISOFIX points. 

The RX scored a maximum five ANCAP stars in January 2016.

The GLC63 is covered by Mercedes Australia’s usual five-year/unlimited kilometres warranty.

As for maintenance, Mercedes offers service plans, spanning three to five years. Three years will cost you $5025, $6455 for four years and five years is priced from $7180. Servicing intervals are 12 months or 20,000km, whichever comes first.

Lexus offers a fence-sitting four year/100,000km warranty with roadside assist thrown into the bargain for the same period. 

Service intervals arrive at 12 month/15,000km and there is, sadly, no capped-price servicing.

Lexus will, however, promise you a car for the day or come and get your car from you and drop it back when the service is done. And it will be washed and vacuumed. The website makes a big deal about that.