I installed them in a Picanto. The front ones are perfect. They fit nicely and feel like they are from the manufacturer. The back ones, however, are a problem. I had to leave out the back seat backrest because the seat belts would be useless. I installed the bottom part but had to make modifications, with holes, etc.
The front seats get 5 stars. The back seats get 0 stars. Cost. They should be cheaper in my opinion.

Very good material and soft, just in Ibiza 2004 the front and passenger seat belts were not long enough to reach underneath, but I tightened them between the seats and it's okay

The back covers are not detachable, so you have to tear them apart for the middle zone, which is unacceptable. Also, the headrests do not fit well and wrinkle. For 70 euros, it is by no means worth it

Just received them
They are not bad, I just expected something better for their price
Also, for those who are interested, they are not suitable for adjustable seats
Also, if you have an armrest in the middle, there is no hole, so it's useless
You also need to cut the middle back zone to place it as best as you can
At 50€ it would be the best price
I wouldn't choose them again for the above reasons.

We put them in a Toyota Yaris 2016. They are awesome, apart from giving an extra appearance, they are also one of the best in terms of quality that I have seen. Also, for the driver and the passenger, the cushions provide a small assistance for body posture. Finally, they are a bit difficult to apply since they have many elastic bands for stretching that you pass through support brackets, and in some areas, you may need scissors, however, they are value for money.