The short answer
Neither car is a bad choice. Both are comfortable, dependable daily drivers with a V6 and similar fuel use. The decision comes down to what you value more: the Mercedes gives you the richer, more executive cabin, and the Lexus gives you more standard equipment and fewer expensive surprises.
At a glance
- Pick the ML350 if cabin feel matters most to you: wood trim, a panoramic roof and the biggest boot of the two.
- Pick the RX350 if you want the most equipment for your money and a car that is simple to live with.
- Either way, the condition and history of the exact car in front of you matters more than the badge.
The case for the Mercedes ML350
The 2012 ML350 opened the W166 generation, which ran until 2019. It still looks like a proper full-size executive SUV, and that presence is a big part of why people want one.
- Outside: LED headlamps, fog lamps, 19 inch wheels, power folding mirrors with blind spot warning, running boards and a powered tailgate.
- Boot: about 36 cubic feet with the rear seats up, and the seats fold flat to roughly double that. It is wider than the boot in the Lexus.
- Cabin: real wood trim, soft leather, eight-way power seats and a panoramic sunroof, which the RX in our video does not have.
- For rear passengers: air vents, cup holders in the armrest, a 12 volt socket and a 115 volt socket for a laptop.
- Driving aids: hill descent control, traction and stability control, dual zone climate control and paddle shifters. The BlueEfficiency badge marks the more fuel-conscious version.
The summary from the Mercedes side of the argument: the comfort and plushness of this cabin is what you would miss in the RX350.
The case for the Lexus RX350
The RX350 is the best selling RX there has been, and the argument for it is about what you get without paying extra.
- Standard kit: smart entry and push button start come as standard on the Lexus. On the ML350 they were options, so the one you are looking at may not have them.
- Seats: heated and ventilated front seats, and rear seats that recline and adjust, which makes up for the narrower boot.
- Three keys, three drivers: the car remembers a seating position for each key, so it adjusts itself to whoever unlocks it.
- Rough roads: our Lexus host argued it has the better approach angle and ground clearance of the two.
- Under the bonnet: a naturally aspirated V6 with about 270 horsepower, front wheel drive with all wheel drive as an option, and a famously tidy engine bay.
| Mercedes ML350 (2012) | Lexus RX350 | |
|---|---|---|
| Headlamps | LED | Xenon |
| Smart entry and push start | Optional | Standard |
| Sunroof | Panoramic | Not on the car we filmed |
| Boot | Wider, about 36 cubic feet | Narrower, but the rear seats recline and adjust |
| Front seats | Heated, eight-way power | Heated and ventilated |
| Phone connection | Bluetooth only | Bluetooth only |
| Fuel use | About 19 miles per gallon | About 20 miles per gallon |
The table reflects the two cars we filmed and what the hosts said about them. Equipment varies by trim and by the market the car was built for, so check the exact car you are buying.
Running costs: the part that decides it
Fuel use is close enough that it should not decide anything. The difference the hosts kept returning to is the steering. The ML350 uses an electric steering rack, and if water gets to it, which is a real risk on flooded roads, it is very expensive to put right. Take that one item out and their view was that the two cars cost about the same to maintain.
So before you pay for an ML350, have the steering checked properly and ask how the car has been used in the rainy season. Before you pay for an RX350, confirm which options it actually has, because the specification varies a lot between cars.
How to choose
If you want the car that feels more special every time you sit in it and you are prepared to maintain it carefully, the ML350 makes the stronger case. If you want the car that asks less of you and still gives you a quiet, well equipped cabin, the RX350 is the safer buy.
Whichever way you lean, work out the yearly cost before you commit. The purchase price is only the start.