Lexus RX300 vs Mercedes-Benz Gls450

What's the difference?

The Lexus RX300 is luxurious but affordable, making it great value and superbly comfortable, with a high level of fit and finish. Fear not about the four-cylinder engine being small – it makes plenty of grunt and handles daily duties perfectly well.

Which would you go for: An entry level Lexus RX300 or a top-of-the-range Mazda CX-9? Tell us what you think in the comments below.

The GLS450d impresses as an entry-level grade, as it’s a more family-friendly allrounder than the specialised AMG and Maybach variants. Its combination of a torque-rich diesel 48V hybrid drivetrain, air-cushioned suspension and plush interior are as well suited to luxury urban travel as they are to grand touring, where its heavy towing and generous load-carrying capabilities can shine. Whether it’s worth around $200K drive-away, only those who shop at the top end of town can decide.

I've mentioned the Spindle grille and its jewellery-like appeal, and even the sharp edges of this SUV make the RX300 look like a carved gemstone, but I'm not the biggest fan of this vehicle's proportions. I think the door-to-window ratio is a bit off. There's just too much door for my liking.

That said, I'm intrigued by the craftmanship, the attention to detail and the use of materials, which make this SUV both pretty and intriguing.

The cabin mixes the plushness of cushioned surfaces on the dash and the armrests  with pleasing design elements, like the swooping aluminium trim, which zig-zags its way from the instrument cluster to the passenger's side of the centre console.

The giant media display is impressive, but the functionality is awkward, to say the least, but more on that in the practicality section below.

The Luxury is the entry grade into the RX model and so comes with smaller wheels than the F Sport and Sports Luxury above it, but it does score roof rails, dual chrome exhausts, a roof-top spoiler and rear privacy glass.

How big is the RX300 Luxury? The dimensions show it to be 4890mm long, 1895mm wide and 1690mm tall.

How do the looks compare with rivals such as a Jeep Grand Cherokee, a Mazda CX-9 or a Land Rover Discovery? Hmm, each has its own distinctive styling, with the Jeep having brutish American looks, the Discovery boasting prestige British off-roader personality and the Mazda an elegant air that's way beyond its price point.

So why haven't I mentioned the Mercedes-Benz GLE or BMW X5? Because they're at least $20K more than the RX300 Luxury, which costs around $72K. If, however, you can stretch the budget to an RX 350 Sports Luxury then you will be crossing the $100K threshold into Benz and Bimmer territory. So let's talk about price.

This is an imposing vehicle in extravagant S-Class tradition, riding on an expansive 3135mm wheelbase and stretching more than 5.2 metres (5215mm) long and more than 2.0 metres (2030mm) wide with a turning circle that's nudging 13 metres.

However, it’s just under 1.8 metres (1798mm) tall, so there’s no clearance issues when accessing multi-storey carparks. And with its side-steps (or ‘running boards’ in nostalgic Benz speak) most adults can step rather than climb aboard, although passengers of shorter stature during our test noted that assist handles on the A and B pillars would be handy.

Central to its sophisticated chassis design is adaptive air suspension, which uses a pneumatic or ‘airbag’ form of springing with adaptive damping to continuously optimise ride comfort and handling response according to road conditions and driving dynamics (see Driving).

The GLS’s styling is clean and uncluttered with tasteful restraint evident in its chrome and satin-chrome highlights, yet it projects a majestic quality with its prominent four-louvre grille and elegantly spoked alloy wheels.

The spacious and sumptuous seven-seat interior is visually pleasing and practical, with a subtle blend of surface treatments, contrasting tones, lots of soft-touch surfaces and exposed stitching. This is combined (thankfully) with physical dials, switches and ‘piano key’ buttons to control numerous interior functions, in preference to distracting touchscreen prompts.

The RX300 is a five-seater SUV and, while it would be even more practical if there was a third row, the cabin is impressively spacious.

Have a look at my photo of the entry to the RX300's back seat – that's a big doorway  for a car. Parents will understand the value of wide-opening doors and these ones made it easy for my child to climb into his car seat and for me to buckle him up. Head and legroom in the back seats are also good, even for me at 191cm tall, while the flat floor makes it easy to 'scoot' across from one side to the other.

There are two cupholders in the fold-down centre armrest in the back and small door pockets, but storage up front is better, with huge pull-out door pockets, two more cupholders and a large centre-console bin.

There's a wireless charger in the hidey hole in front of the shifter, plus six USB ports on board - the rear passengers have two of their own in the back of the centre console and the rest are up front.

The second row doesn't come with climate control, but the directional air vents back there got a workout over the 40C days we had over summer.

The RX300's boot has a cargo capacity of 506 litres, measured to the top of the second-row seat back.

Now,  the media system. Yes, it's a tech thing, but I'm calling out it out as impractical. The functionality of the trackpad used to navigate around the screen is frustratingly awkward. I think 12 swear words in a row came out of me on one occasion (no child on board, obviously), just trying to use the sat nav. The layout of the display menu is also confusing and non-intuitive.

Although it has a hefty 2655kg kerb weight, our test vehicle’s 3420kg GVM rating provides a useful 765kg of load capacity, which should comfortably absorb the combined weight of up to seven occupants and light luggage. Or with the third row of seating folded, five occupants and heavier luggage.

It’s also rated to tow up to 3500kg of braked trailer and with its sizeable 6920kg GCM (or how much weight it can legally carry and tow at the same time) it can carry its maximum load while towing its maximum trailer weight.

So, that’s commendable practicality, given it would be well suited to owners that need to tow large caravans, boat trailers, horse floats etc in style without having to compromise much (if at all) on either passenger numbers or luggage capacity.

Driver and front passenger space and comfort is exceptional, as you’d expect. Storage includes a large glovebox plus a bottle holder and bin in each door. The front of the centre console has two USB-C ports, wireless phone charging and heated cupholders, while the rear of the console has a large storage box with a third USB-C port and padded lid that doubles as a comfy elbow rest.

Even tall passengers in the second row of seating enjoy spacious comfort, given I’m 186cm and with the driver’s seat set in my position I have ample knee clearance, foot room and head space.

However, the central passenger must contend with a transmission tunnel in the floor and shoulder room would be squeezy for three large adults, which is okay for short trips but a maximum of two would be ideal for longer journeys.

The rear of the centre console also treats second-row passengers to a pair of USB-C ports, adjustable air-vents and a control panel that allows independent climate adjustment.

There’s also a large bin/bottle holder in each door plus storage nets on each front seat backrest. The centre seat backrest folds flat to allow long items (skis etc) to slot between the outer backrests. And it also serves as a fold-down armrest, containing two cupholders and a lidded slimline compartment that’s ideal for hidden phone storage.

The third row is uncommonly spacious, even for tall people, with padded armrests on each side containing cup holders and twin USB-C ports.

The carpeted rear luggage area has four load-anchorage points, a first aid kit and 12v socket. With the third-row seats upright it offers 355 litres of load volume, which increases to 1350 litres with the third row folded and 2400 litres (or 2.4 cubic metres) with both the second and third rows folded.

Our Polar White test vehicle, which is the base grade in the three-tiered GLS range, comes standard with a 3.0-litre inline six-cylinder turbocharged diesel engine with 48V mild hybrid technology, nine-speed automatic transmission, permanent all-wheel drive and active air suspension for a list price of $189,100.

This pricing is higher than comparative entry-level grades offered by the two marques which dominate sales leadership in this segment, comprising the BMW X7 xDrive40d M Sport ($179,500) and Lexus LX500d AWD ($158,700).

The GLS450d’s standard features include 22-inch AMG alloy wheels with Continental 325/40 R22 tyres and a collapsible spare, ‘AMG Line’ body styling enhancements, aluminium-look illuminated side-steps with non-slip rubber studs, multi-beam LED headlights and more.

Step inside the keyless interior and you’ll find ‘Hey Mercedes’ voice activation, fingerprint scanner (which memorises individual comfort settings for up to seven users), panoramic sunroof, heat-insulating dark-tinted rear privacy glass and the ‘Premium Plus Package’ that includes heating/cooling for the front seats, heated rear seats, head-up display, separate front/rear climate control zones, heated cupholders and more.

There’s also a concert hall-like Burmester surround sound system controlled by a central touchscreen with digital radio and Apple CarPlay and Android Auto connectivity, plus wireless phone charging, multifunction Nappa leather sports steering wheel and USB ports front and rear.

Driver assistance includes the ‘Parking Package’ (360-degree camera, active parking assist and transparent bonnet), ‘Mirror Package’ (auto-dipping rear-view mirror and electric folding door mirrors with puddle lamp projection of the brand logo) and ‘Driver Assistance Package’ (blind-spot assist, exit warning, speed sign recognition, lane keeping etc) all included as standard equipment.

Of course, Mercedes-Benz offers numerous extra-cost options including a 3500kg towing package plus interior, exterior, suspension and wheel enhancements (including Nappa leather trim) for those who want their GLS with the lot, which can easily push the list price beyond $200K.

The RX300 has a 2.0-litre four-cylinder turbo-petrol engine making 175kW and 350Nm, with a six-speed automatic transmission. This peppy four-cylinder gives the RX300 a completely different feel to the lethargic-but-powerful oomph of the RX350 and its naturally aspirated V6, even though it doesn't make a great deal more grunt, at 221kw and 370Nm. There's a difference in fuel consumption, too – find out how different below.

Is the RX300 all-wheel drive? Nope, it's a front-wheel drive. Only the RX350 and RX450h are AWD.

The GLS450d comes standard with a 3.0-litre turbocharged inline six-cylinder diesel producing 270kW of power at 4000rpm and 750Nm of torque between 1350-2800rpm.

This is paired with a 48V mild-hybrid system comprising a 48-volt battery (charged by regenerative braking) and an integrated starter-generator which provides both seamless engine stop-start and up to 15kW/200Nm of extra power and torque during acceleration.

A nine-speed torque converter automatic provides the choice of manual shifting using the steering wheel-mounted paddles, along with several selectable drive modes.

The active all-wheel-drive system continuously adjusts the engine’s torque delivery between front and rear axles (and individual wheels as needed) to maintain optimum traction and handling.

Lexus says the RX300, with its 2.0-litre four-cylinder turbo-petrol engine, should use 8.1L/100km of premium unleaded after a combination of open and urban roads. My own testing over 375.4km - taking in motorways, city and suburban call-of-daycare drop-off-duties - had our RX300 using 11.79L/100km, measured at the petrol pump. The real-world results almost always exceed that of the manufacturer's claims so you can expect the V6-powered RX350, with its claimed 9.6L/100km, to have a much higher mileage again after the same kind of usage.

Mercedes-Benz claims official combined consumption of 7.8L/100km and the dash display was showing 9.0 when we stopped to refuel at the completion of our 368km test, which included the usual mix of suburban, city and highway driving with up to five passengers at times and light luggage.

Our own figure, calculated from fuel bowser and tripmeter readings, was close at 9.5 which is outstanding sub-10L/100km economy for such a substantial vehicle in mostly metropolitan use. Therefore, based on our own consumption figure, you could expect a real-world driving range of around 950km from its 90-litre diesel tank.

Good seats are the start of a good driving experience and I've not met a Lexus that doesn't have superb pews – from the uber luxury models, such as the LS500 and ES300, to sports cars such as the RCF or LC500, they all have supportive and comfy ones. Lexus somehow manages to  combine the comfort of a lounge chair yet still holds you firmly, all while placing you in a great driving position. The RX300 is no different. Large enough to fit me and my 191cm frame, yet bolstered enough to feel snug.

As for performance, the RX300, with its four-cylinder turbo-petrol engine with its six-speed automatic, is responsive and a bit hyperactive feeling. It's a very different sensation to piloting the RX350, which has a V6 and delivers its grunt in a more linear and lethargic fashion. Having driven both back-to-back I'd say the V6 and its eight-speed auto suits the RX personality better, but the 300 is a car that would have had a school report card that read: "Lots of potential, but lazy".

That said, plant the right foot and the RX350 will get the message to hurry up and can do the 0-100km/h sprint in eight seconds flat. The RX300 is keen but can't match it, with  a time of 9.2 seconds.

Either way, the ride comfort is excellent, although body control could be better - the speed bump and roundabout route I take to do the preschool drop off caused it to  get the wobbles, but give the RX300 a motorway and it'll cruise beautifully.

Forward visibility is good but vision through the tiny rear-quarter window (it's even smaller than it looks) while reverse parking isn't great.

It’s an enjoyable vehicle to drive, with multiple power adjustments for the seat and steering wheel combined with a large left footrest which provide supreme driver comfort and support.

The powerful and responsive turbocharged six-cylinder diesel and nine-speed auto are well suited to this application. The engine’s ample torque provides spirited acceleration from standing starts, taking only six seconds to reach triple-digit speeds.

This drivetrain would be well suited to heavy towing duties, given the 48V mild-hybrid system can contribute an extra 200Nm (in addition to the engine’s 750Nm), which raises the total theoretical torque output to almost 1000Nm.

The active air suspension provides a wonderfully cushioned ride that floats over bumpy roads, while maintaining excellent handling response and surprising agility. These commendable chassis dynamics, combined with the powerful and responsive drivetrain, makes the vehicle feel smaller and lighter than its dimensions and kerb weight would suggest.

Overall, it’s difficult to fault from a driver’s perspective, with the only exception being the voice activation function. This is often triggered by words or phrases other than ‘Hey Mercedes’ resulting in regular interruption of conversations. This needs some fine tuning.

The GLS does not have an ANCAP rating as it’s yet to be tested, but comes standard with a suite of passive and active safety features including nine airbags, auto emergency braking (AEB) with pedestrian detection and junction assist, blind-spot monitoring, traffic sign recognition, head-up display, rear cross-traffic alert, lane-keeping, adaptive cruise control with ‘distance assist’ (autonomously brakes/accelerates in heavy traffic), front/rear parking sensors, 360-degree camera and more.

There’s also two ISOFIX and three top-tether child seat anchorages in the second row, plus two more of each in the third.

Lexus recommends servicing the RX300 annually or every 15,000km, with the first three services capped at $595.

The duration of Lexus's factory warranty is four years/100,000km, which is a bit longer than BMW and Benz's coverage, but behind the five-year/unlimited-kilometre warranties of the mainstream brands.

The GLS comes with a five-years/unlimited km warranty (better than BMW and Lexus) and five years of roadside assistance. Scheduled servicing is every 12 months/25,000km whichever occurs first.

Mercedes-Benz offers capped-price pre-paid servicing packages with three, four or five-year terms. For example, the total upfront cost of the minimum three-year term is $4090, or an average of $1363 per service.