The Mercedes M-Class SUV (since renamed the GLE-Class), which includes models like the ML350 and ML550, is one of the most popular mid-sized luxury SUVs sold today in the United States, competing with SUVs like the Acura MDX, Acura RDX, Audi Q5, Audi Q7, BMW X3, BMW X5, Volvo XC60 and Volvo XC90. Many professionals with families choose it when looking for a stylish yet safe mid-sized SUV for their families. I’ve written about it as one of the safest SUVs you can buy for side impact protection, and it’s about as good as it gets in that regard. It’s also one of the safest SUVs as measured by actual driver death rates.

Despite their maintenance costs, the M-Class SUVs represent a good choice for families with large budgets who are interested in transporting up to 3 children. I borrowed an ML350 this past week in order to figure out which car seats would fit well and which wouldn’t in one. However, before discussing what I found for 3 across installations, let’s take a look at some of the important elements of car seat safety, in terms of rear-facing, forward-facing, and appropriate boostering.

In my experience, the best protected children in vehicles are the ones who rear-face as long as they can (ideally until 4!), and then forward-face as long as feasible (ideally until 8!), and then booster until they can use a regular seat belt (which typically happens between 10 and 12). These guidelines keep your children as safe as possible by keeping them in the right orientations as long as possible.

However, if you’re going to make the best use of best practices, you need to know which car seats will and won’t fit well in your Mercedes M-Class. That’s why I wrote up this 3 across installation guide, and why I write so many car seat reviews and test out my recommended car seats in every vehicle possible.

If you’re in a hurry and want the best, pick up 3 Clek Fllos or 3 Clek Foonfs for 3 across; they offer the highest rear-facing weight limits combined with the narrowest seat widths among mainstream convertibles. However, you can make things work with a number of other car seats, which I’ve described below. You can access the complete 3 across guide for every vehicle here and the complete list of recommended seats here. The Canadian recommended list is here. 3 across car seat images are courtesy of Wikipedia.

2016 Mercedes GLE-Class (W166)

Guaranteed 3 across installations:

Clek Fllo (x3).

Clek Foonf (x3).

Diono Radian / RXT (x3).

Combi Coccoro (x3).

Maxi-Cosi RodiFix, Britax Marathon G4, Diono Radian / RXT.

Diono Radian / RXT, Diono Radian / RXT, Britax Parkway SGL.

The initial generation of the GLE-Class is the M-Class under a new name. As with the prior M-Class, it’s 189 inches long and 76 inches wide, which means you’re going to have a relatively easy time achieving 3 across installations with most car seats from a side to side perspective. As usual, try seat belt installations if you have trouble with LATCH setups, as you’ll have more room with seat belts than you will with LATCH anchors. Keep in mind that Mercedes doesn’t allow you to borrow outboard LATCH attachments when installing a seat in the center position.

2012, 2013, 2014, 2015 Mercedes M-Class (W166)

Guaranteed 3 across installations:

Clek Fllo (x3).

Clek Foonf (x3).

Diono Radian / RXT (x3).

Combi Coccoro (x3).

Maxi-Cosi RodiFix, Britax Marathon G4, Diono Radian / RXT.

Diono Radian / RXT, Diono Radian / RXT, Britax Parkway SGL.

This generation of the Mercedes M-Class is 189 inches long and 76 inches wide, which means you’re going to have a relatively easy time achieving 3 across installations with most car seats from a side to side perspective. As usual, try seat belt installations if you have trouble with LATCH setups, as you’ll have more room with seat belts than you will with LATCH anchors. Keep in mind that Mercedes doesn’t allow you to borrow outboard LATCH attachments when installing a seat in the center position.

2006, 2007, 2008, 2009, 2010, 2011 Mercedes M-Class (W164)

Guaranteed 3 across installations:

Clek Fllo (x3).

Clek Foonf (x3).

Diono Radian / RXT (x3).

Combi Coccoro (x3).

Maxi-Cosi RodiFix, Britax Marathon G4, Diono Radian / RXT.

Diono Radian / RXT, Diono Radian / RXT, Britax Parkway SGL.

This generation of the Mercedes M-Class is also approximately 189 inches long and 76 inches wide, which means that just about any car seat combination you can fit into the current generation will also fit into the prior generation, with very few exceptions. The rule about not borrowing LATCH anchors remains the same, and I’ll continue to recommend using seat belts to make the most of your space, although with this kind of width, you’re unlikely to need it.

1999, 2000, 2001, 2002, 2003, 2004, 2005 Mercedes M-Class (W163)

Guaranteed 3 across installations:

Clek Fllo (x3).

Clek Foonf (x3).

Diono Radian / RXT (x3).

Combi Coccoro (x3).

Maxi-Cosi RodiFix, Britax Marathon G4, Diono Radian / RXT.

Diono Radian / RXT, Diono Radian / RXT, Britax Parkway SGL.

The initial generation of the Mercedes M-Class is 181-183 inches long and 72 inches wide, which means it’s about the width of a mid-sized vehicle. This will easily be the most difficult generation of the M-Class to achieve successful 3 across installations in, but it’s definitely still possible, especially when you consider all the car seats people are able to fit into mid-sized cars. My recommendation of turning to seat belts over LATCH installations will be most important here.

If you find the information on car safety, recommended car seats, and car seat reviews on this car seat blog helpful, you can shop through this Amazon link for any purchases, car seat-related or not. Canadians can shop through this link for Canadian purchases.