We took the Tesmat with us (me, wife, 35 pound dog) on our road trip, camping twice (not back-to-back nights) in our Model 3. Overall, I give the Tesmat an A. It performs very well, and as advertised. The major problem, the tightness of the space, is an issue that is going to apply to any type of mattress for the Model 3. In balance, I give 5 stars, because Tesmat does what it says it does very well.
Generally, the Tesmat's foam is soft, but firm enough to feel supportive. The fit into the rear of the vehicle is perfect. The microfiber sheet is comfortable, and the soft surface of the Tesmat feels much better than the rubbery (or feltlike rubber texture) of most air mattresses. In fact, we used the Tesmat to sleep at one of our destinations on the floor of the room instead of the air mattress the host offered us. This just confirmed for me that the major problem with the Tesmat is really an issue with the Model 3—the small size available—and not the mattress.
So, the big issue is ironically the small size of the rear compartment of a Model 3. While the Tesmat manages to be a regular twin size mattress, folks that are not used to sharing a twin bed with another adult are going to be much more cramped than they are used to being. And, unlike most beds, the edge of the bed is not empty space but the unyielding frame of the car. Moving in and out of the mattress can feel awkward, as you are climbing through the rear door in an unusual position. And moving around at night can result in bumps against the top of the trunk. Again—these are issues that are going to apply to any mattress for the Model 3. Also, when one person slept on the mattress alone (naps during the day, mostly) they felt the size issue much less acutely.
Pros:
1) The Tesmat is super light, easy to unfold and 'install' by one person.
2) The Tesmat is quite soft and comfortable.
3) The Tesmat is perfectly shaped and sized to take up the entire rear of the Model 3, maximizing available sleeping area.
4) The Tesmat is very easy to roll and store in included bag. The rolled mat stores easily in the car.
5) Privacy screen installation is easy.
6) I feel the price is very reasonable for the value. Without Tesmat, I would have needed to get a tent, tent pad, and an air mattress or sleeping mat, to even begin to replicate what we had with Tesmat and the car. And even then I wouldn't be able to fully replicate the benefit of sleeping in the car, such as having more physical security, full climate control, and access to USB/Bluetooth etc. that are available in the car.
7) Tesmat, and accessories, appear to be of high manufacturing quality. We noticed no defects and nothing looking shoddy or like it was cheaply made.
Cons:
1) I stress, not Tesmat's fault, but you're sleeping in a car and therefore the space is tight. This will not magically make it feel spacious. Although, the arched glass roof does keep the car from feeling claustrophobic at all.
2) The privacy screen does not fit tightly to the windows, and tends to come untucked when going in or out of the car. It fills its purpose, but not as polished as I think it could be.