Mercedes-Benz E400 vs Lexus Rz

What's the difference?

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.

Smooth, quiet, quality sums up this new and improved Lexus RZ. But will tricky new tech like steer-by-wire and a manual mode in the F Sport's auto transmission be enough to sway more premium electric SUV buyers its way? Fold in this car’s value proposition as well as the brand’s spectacular ownership package and it just might be.

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

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.

Not a tremendous amount of change in terms of exterior design for this update with the brand’s signature angular treatment retained including a prominent snub nose and 20-inch rims on both variants of the car.

The top-spec F Sport picks up extra aero-focused elements, particularly around the lower bumper at the front, as well as aero covers on the wheels and at the back a spoiler on the tailgate as well as a faux diffuser at the bottom of the lower bumper.

Not much has changed inside either except for a steering wheel-shaped elephant in the room in the form of a yoke that goes with the steer-by-wire function on the 550e F Sport. A significant, eyebrow-raising departure.

However, the curved instrument binnacle, central 14-inch multimedia screen as well as the design of the centre console remain unchanged. 

Having said that, there are new ‘laser-patterned’ designs in the door card trims and dynamic lighting graphics in the doors, as well.

The functionality of the touch-dimmable panoramic roof has also been improved and it works beautifully.

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 a fraction over 4.8m long, close to 1.9m wide and a bit more than 1.6m tall, with a 2850mm wheelbase, the ZR is a sizeable machine. 

There’s plenty of breathing space in the front and in terms of practicality the first thing that jumps out, or rather it doesn’t, is the lack of a conventional glove box.

But there is a large box between the front seats to take its place, with the lid (which doubles as a centre armrest) performing the Lexus party trick of being able to open towards the driver or passenger.

There are two cupholders in the centre console with a wireless charging pad ahead of them, plus decent bins in the doors for bottles and other bits and pieces. An additional tray sits under the main, flying buttress-style upper console.

For power and connectivity, there are USB-C sockets for charging and media as well as a 12-volt socket in the lower console section.

Getting into the back is easy thanks to wide-opening doors and a large entry aperture and seated behind the driver’s seat set for my 183cm position I’ve got hectares of leg- and headroom. Shoulder room is best for two full-size adults rather than three, which would be a short-journey squeeze. Three up to mid-teenage kids will be fine.

In terms of storage there are pockets on the front seatbacks, bins able to hold a large bottle in the doors and two cupholders in the fold-down centre armrest. Individual ventilation control for rear seat passengers is always welcome. 

Then for power, there are two USB-C outlets and a ‘house-power’ socket underneath them. The 550e F Sport also includes heating controls for the two outer rear positions.

Lower rear axle packaging enhances boot space with a generous 522 litres on offer, expanding to 1451L with the 60/40 split-folding second row lowered. Tie-down anchors and bag hooks are a thoughtful touch and there are handy storage boxes under the flat floor, ideal for charging cables. 

The standard power tailgate is nice, while a repair-inflator kit instead of a proper spare isn’t. Braked trailer towing capacity is a handy 1.5 tonnes.

Lexus says final price and specification for the new RZ will be confirmed closer to its local arrival in the first part of next year. But as a guide, the current entry-level RZ450e in Luxury spec costs around $120,000 before on-road costs. Go for the full-fat Sports Luxury and you can add $10,000 for a $130K MSRP.

Let’s take an educated guess and add a not outrageous five per cent price increase for this update which would bump the new RZ500e (to be offered in Luxury and Sports Luxury grades) past a $125K entry point and move the new RZ550e F Sport flagship close to $140K.

If that was the case, rivals will include the Audi Q8 e-tron (from $153,984), BMW iX (from $136,900), Genesis GV70 Electrified Signature ($125,858) and Polestar 3 (from $118,420). 

Worth noting you could buy two examples of the Tesla Model Y Dual motor Long Range ($68,900) for the same money.

In this part of the market it’s fair to expect a healthy list of included features and the RZ doesn’t disappoint.

Aside from the performance and safety tech we’ll get to shortly, standard specification highlights include a 14-inch multimedia touchscreen, a digital instrument display, a dimmable panoramic roof, 14-colour ambient cabin lighting, 20-inch alloy rims, LED headlights, cornering lights and a 360-degree camera system.

There’s also synthetic leather trim (synthetic suede on F Sport), built-in nav, power-adjustable heated front seats, multi-zone climate control and more. Not bad.

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.

Both versions of the new RZ are powered by dual permanent magnet synchronous motors, one in the front, one at the back, each producing 167kW and 269Nm. 

Total output is 280kW for the 500e (up from 230kW in the 450e), with a little more juice released from the motor combination for the 550e at 300kW.

A single-speed transmission sends drive to both axles and the RZ550e F Sport features ‘Interactive Manual Drive’ designed to give the sensation of manual gear shifts in a BEV. More on that in the Driving section.

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.

The RZ500e and 550e are fitted with a 77kWh lithium-ion battery delivering a claimed (WLTP) range of 450 and 456km, respectively.

Claimed 10-80 per cent charge time, using its full 150kW DC fast-charge capacity, is 30 minutes or a handy three and half hours at maximum 22kW AC capacity.

Energy consumption on the combined (urban/extra-urban) cycle is 18.2kWh/100km (WLTP) for the RZ500e and 18.4 for the 550e.

Over several hundred kilometres of B-road and freeway running as well as pottering through slow-speed villages on the launch we saw an average of 19.3kWh/100km in the 500e and 20.1 in the 550e F Sport, which is pretty handy.

And the (very) good news is two AC charging cables, installation of a home charger and three years’ complimentary charging across the Chargefox network is included. Nice!

Sure, the E400 Cabriolet can drive itself, but we’re equally pleased to note that it’s still a lot more fun handling the steering duties yourself.

And that is mostly due to that fabulous engine; quiet and effortless at city speeds, rorty and enthusiastic at pace, and genuinely angry with the drive setting switched to their most hardcore Sport+ mode.

We’ve already spent time in the sedan version, and while this Cabriolet is heavier (1935kg vs 1820kg) and slightly slower to 100km/h (5.5sec vs 5.2sec) it doesn’t immediately feel it behind the wheel, with a similar and satisfying lurch into the future when you plant your foot.

But hard charging is not what this car is about, and the E 400 is at its peachy best when rolling about the city or the ‘burbs with the top down, and the warm summer air washing through the cabin.

In its normal drive settings, the steering is light but engaged, and the ride on offer from the standard air suspension is outstanding, cosseting the cabin from all but the very worst road imperfections, while the torque from the V6 serves up effortless, unobtrusive acceleration.

With the roof up, Merc’s designers have done a stellar job of hiding the fact this thing is a convertible at all. It’s a solid-feeling cabin with the fabric roof fastened, and the cabin is quiet and free from wind noise.

It’s a hefty machine at 2.1 tonnes, but Lexus says the RZ550e F Sport will accelerate from 0-100km/h in 4.4 seconds, with the 500e only marginally slower at 4.6sec.

In straight-line acceleration Lexus says front to rear power distribution varies between 60:40 to 100 per cent rear to suppress pitching and “produce a more direct acceleration feel”. 

And the RZ is indeed quick. Apply your right foot at just about any speed and the car rockets ahead with satisfying enthusiasm.

The F Sport’s ‘manual’ mode allows you to shift through eight virtual ‘ratios’. Press the ‘M’ button on the console and bingo, you have slim steering wheel-mounted paddles to control them.

At anything above a light accelerator application you’ll feel a jolt on upshifts, but it’s rather unpleasant. Sure, you want some sense of a gear change, but you feel it in your core. Check out the video review to see how much it can shake you around. 

A synthetic soundtrack Lexus refers to as the “BEV Sound”, vaguely echoing an internal combustion engine, is fed through the F- Sport’s audio system and it feels thin and brittle to our ears. Again, check out the audio sample in our video review to see if you agree.

You’ll hear the ‘revs’ rising on up and downshifts but there’s no physical accompaniment with the latter as far as we could sense.

Suspension is strut front with double wishbones at the rear and it’s been given a thorough revision in terms of dampers, springs and bushings in both the 500e and 550e F Sport, with the latter copping some additional fine-tuning in each of those areas.

We sampled 500e and 550e F Sport versions of the RZ on the launch drive in Southern Portugal, covering mostly Aussie-compliant roads with lots of bumps and ruts to deal with. And despite its hefty kerb weight the car copes with these imperfections well.

There’s also been some extra attention paid to body rigidity in this updated RZ, specifically reinforcement of upper sections of the nose and around the boot to keep the car more torsionally stiff.

In cornering the drive distribution ratio is between 80:20 front to rear to RWD-only, according to vehicle speed and steering angle, and the car feels composed and predictable.

The F Sport features the steer-by-wire system, using a yoke rather than a conventional steering wheel and the ratio is such that all you have to do is turn the wheel slightly to generate a response.

It’s smooth and progressive but quick at the same time. You soon become used to it.

While it's unusual to see a small yoke in your hands rather than a steering wheel, it means you have an uninterrupted view through to the instruments, which is a nice side benefit.

However, much like the Infiniti Q50’s system before it, there is no mechanical link between the driver’s hands and front wheels. Steering inputs are relayed by electric signals from a torque actuator to a control actuator.

So, while Lexus says “important feedback filters through without the unpleasant vibration effects of a mechanical connection”, and that’s true, by definition there is no road feel and the wheel feels numb from that point-of-view. Worth noting the mechanically steered 500e feels much the same.

Tyres are Dunlop SP Sport Maxx (235/50 fr - 255/45 rr) which grip hard and remain relatively comfy despite their short sidewall running on 20-inch rims.

One price you pay for the steer-by-wire system’s set-up is a substantial turning circle, so be ready for that.

Braking is by ventilated discs all around, which work nicely, and when you’re not using the manual mode in F Sport the steering wheel paddles allow movement through four levels of regenerative braking.

The most aggressive setting will slow you quite markedly but not to the level of ‘single-pedal’ operation.

Additional sound insulation includes an under-seat rear floor silencer, soundproofing in the door trims as well liberal use of damping sheets, foam, silencer pads, insulators and extra seals. And the car is super-quiet, even for an EV.

In terms of miscellaneous observations, the front seats on both versions remained comfortable and supportive over long stints behind the wheel (and yoke!).

Slow speed manoeuvring is assisted by a 360-degree overhead camera view with a translucent trace of the car in the centre, as well as a high-quality reversing camera. Vision across the car and through to the back is good, anyway, but the extra tech helps in the slow speed stuff. 

There’s also a sensible mix of physical dials and on-screen controls and the touchscreen menus are easy to use. Especially handy when you’re racing to the function that turns off the intensely annoying over-speed warning.

The RZ received a maximum five-star ANCAP assessment in 2022 scoring 80 per cent-plus results in all areas.

As you’d expect, a full suite of driver-assistance tech is onboard including auto emergency braking (AEB) with car-to-car junction, crossing and head-on functionality as well as pedestrian and cyclist detection, adaptive cruise, lane keeping assist, lane-departure warning, blind-spot monitoring, rear cross-traffic alert, driver fatigue monitoring, tyre pressure monitoring and more. 

The airbag count runs to nine, including side curtains, knee bags for the driver and front passenger as well as a front centre airbag. There’s also multi-collision brake to minimise the chances of subsequent impacts after an initial crash and an auto emergency call function. 

There are three top tethers for child restraints across the second row with ISOFIX anchors in the two outer positions. That’s a comprehensive safety package.

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.

The RZ is covered by Lexus Australia’s five-year/unlimited km warranty and there’s an eight-year/160,000km warranty on the drive battery, which is in line with the RZ’s key competitors.

Recommended maintenance interval is 12 months/15,000km, which is relatively brief for an EV. 

Capped-price servicing is yet to be confirmed, but for reference the outgoing 450e runs to $395 for each workshop visit up to a maximum of five years/75,000km. That’s sharp pricing in this part of the market.

The RZ also qualifies its owner for ‘Platinum Electrified’ benefits under the ‘Lexus Encore’ ownership program. That means everything from access to “exclusive offers and events” to a complimentary service loan car, five years’ roadside assistance, valet parking at selected locations, airport lounge access and (heaps) more, including the charging benefits mentioned earlier. Hard to argue with that.