We are mom-supported. When you buy through links on our site, we may earn a commission.

Diono Monterey 4DXT High Back Booster Car Seat Review

The Monterey 4DXT is one of the latest models in Diono’s line. It has several additional features compared to the Monterey XT and is designed with safety and comfort in mind. It’s a great choice for parents who want to keep their child in a booster longer—its high height and weight limits allow it to be used with children up to age 12.

Let’s take a closer look in this Diono Monterey 4DXT High Back Booster Seat review.

Diono Monterey 4 DXT Latch Booster, Plum

Height and Weight Limits

The Diono Monterey 4DXT has an adjustable headrest and side panels that grow with your child up to age 12. It also works in a backless booster mode once your child outgrows the back until they are tall enough to use the lap belt in the car.

Diono Monterey 4 DXT Latch Booster, Plum

The seat can be used for children between 38-63” tall and weight between 40 and 120 pounds. You should stop using the back of this seat once your child’s ears are above the booster seat in the headrest’s highest position.


You can see the added sturdiness if you look at this compared to the Monterey XT. The whole design is thicker because of the padding but designed so it does not make the booster any bulkier.

There are three layers of protection in this booster seat when it is used in its backed mode. The first layer is foam added on the inside for shock absorption. The second is a molded shell casing. Finally, an EPS layer on the outer shell absorbs impact and distributes it away from your child.

Diono Monterey 4 DXT Latch Booster, Plum

Even with all the padding, the exoshell panels on the side at a breathability feature to this car seat. This is important for maintaining good airflow in the car.


Diono car seats always have an impeccable modern design that’s both thoughtful and practical.


In addition to being comfortable for your child, the Diono Monterey 4DXT is also sleekly designed with comfortable fabrics and luxury AIRTEK foam in the cushioning of the seat base. It comes in vibrant colors including black, dark grey, grey light, red, blue, plum, yellow sulfur, and grey dark wool.

Regarding comfort, the fabric used is a plush memory foam material. It also has an ergonomically contoured base that minimizes the amount of space needed in the car and provides a comfortable seat for even older kids.

Diono Monterey 4 DXT Latch Booster, Plum

Shaped for Comfort

Something else that is great about the contoured base is that it is narrower near the bottom. This ensures you can reach the seat belt of the vehicle easily for buckling. Once your child is old enough to buckle themselves, the seat belt will also be more accessible for them in the Diono Monterey 4DXT. This encourages independence.

The headrest has 11 different positions. This is great for comfort, but also provides the right protection for your little one’s head as they grow. Another benefit of the headrest is that it can be adjusted with one hand.

Diono Monterey 4 DXT Latch Booster, Plum

The seat also reclines, making it a great choice for comfort. With its plush fabrics and comfortable design, this is a great choice for parents who take their toddlers on longer trips and want to prevent them from being uncomfortable.

In backless mode, children will appreciate the deep seat. The deeper seat design allows kids to sit without feeling they are going to slip out of the seat.


The Diono Monterey 4DXT High Back Booster Seat was easy to install. It worked using the LATCH system, which I was already familiar with from other cars. Once installed, you simply use the seat belt guides to position the shoulder and lap belt where they belong on your child’s body.

Even though I didn’t personally have any problems installing the seat, there are video tutorials available on Diono’s website. These are nice to look over to be sure you are installing the booster the right way. The instruction manual was also very detailed. Conveniently, there is a pocket for the manual to be stored on the back of the seat.

Other Considerations for the Diono Monterey 4DXT

The cup holders have a swivel design that lets them be tucked away when they aren’t being used. This is a great choice for parents of multiples who might not have extra space in the backseat. The cup holders are also designed deep and angled, which prevents spills in the car.

Cleaning the seat cover is also easy. The fabric used wipes clean a little more easily than some others I have used. The seat cover is also machine washable with cold water. It is easy to remove and put back on, which I also appreciated.

Diono Monterey 4 DXT Latch Booster, Plum

When not in use, this booster folds completely flat. Since it weighs less than 17 pounds, this makes it compact, lightweight, and easy to carry when folded.

Info from the Manufacturer

One thing that I didn’t like was that it was hard to find information about the Monterey 4DXT on the Diono website. I was able to find product specifications once I downloaded the manual. Hopefully, the Diono company updates this soon—the 4DXT is a newer product.

This comes with a one-year limited manufacturer’s warranty. The warranty does not cover any damage as a result of misuse and is only for workmanship and defects. This is a short period since this booster is designed for your child to use for several years.


  • 11-position adjustable headrest
  • Headrest adjusts with a single hand
  • Easy to install
  • Narrowed base for easier buckling
  • 3 layers of side impact protection
  • Deeper seat base and side wings for more protection
  • Exoshell panels increase breathability
  • Swiveling cup holders
  • Lightweight and folds flat for easy transportation


  • Hard to find specifications and other information on the Diono website while ordering
  • Only has a limited one-year warranty

What is the Difference between the Monterey XT and the Monterey 4DXT?

The Monterey 4DXT by Diono has many of the same features as the Monterey XT with three notable differences.

First, the height and width are adjustable instead of just the height. This lets the highback position support children up to age 12 comfortably. The 4DXT also has a remodeled headrest that is lined with thicker EPP (expanded propylene) foam for more protection and comfort.

The outside of the foam also has breathable exo-shell panels and an improved fabric cover. Bigger cupholders and other comfort features have also been added.

Finally, the base of the seat is smaller by 30mm to make the seat a little less bulky. This was done without reducing the capacity of the inside of the seat of the XT model.

Something to note is that the Monterey 4DXT comes at a higher cost than the Diono Monterey XT. If you want the same quality you expect from the Diono company at a lower cost, the XT might be a good choice. However, the 4DXT is significantly more comfortable and has several luxury features that make it worth the cost.


When Can My Child Transition to a Booster?

Many parents find themselves looking at boosters as soon as their child outgrows their convertible car seat. Before you make the switch, remember that every transition provides your child with a little less protection.

One thing that changes significantly when switching to a booster seat is the harness. Some boosters come with a 5-point harness. These are ideal for kids who might not be ready to buckle themselves or who try to get up while the car is moving.

If your child can handle the booster, the American Academy of Pediatrics still recommends waiting until at least age 4 before making the switch.

When you are ready to make the switch, choose a high-backed booster designed to grow with your child. Look for features like deep side walls, side-impact protection, and an energy-absorbing foam. Even though you could purchase a cheaper backless model, this will not provide nearly the same amount of protection.

When Can My Child Transition to a Seatbelt?

Many car seat manufacturers and state guidelines advise parents to keep their child in a booster until they are at least eight years old. However, this is earlier than most children are ready to ride without a booster seat.

There is a five-step test that you can use to help determine if your little one is ready to ride without a booster seat. Ask the following questions:

  1. Do my child’s knees bend comfortably at the edge of the seat with their feet sitting flat on the floor?
  2. Is my child’s buttocks all the way back in the seat?
  3. Is the lap belt sitting across their hips, across the top of the thighs?
  4. Does the shoulder belt cross at my child’s collarbone?
  5. Will my child sit properly through the entire ride?

If your child does meet all these requirements, they are ready to sit without a booster. For most kids, this does not happen until they are between 10 and 12 years of age.

Final Take

Once your child outgrows their convertible or forward-facing car seat, the Diono Monterey 4DXT High Back Booster is a great next car seat choice.

It has several additional features compared to the Diono Monterey XT and in my opinion, is worth the extra cost. It is more comfortable for older children, which lets you keep your child safer longer. Being suitable for a wide height and weight range, it also is the only booster that you’ll need until they are ready to transition to a seatbelt.

Samantha Davis
Samantha Davis

Samantha Davis is a part-time writer and a full-time mommy of two boys, Apollo (age 5) and Adrien (age 7). She has been working as a writer for seven years and one day plans to run her own writing company. For now, Samantha homeschools her little ones while seeing the country with her fiance who travels for work.