I recently purchased three Graco AFFIX Highback Booster Car Seats for a VW Touareg, Nissan Leaf and a Tesla Model S. The booster seat fits well in all of the cars but the Model S. The canting of the outer edge of the rear Model S seat forces the car seat to be offset to the center, causing the associated seat belt buckle to be unusable. As an immediate fix, I have been using the center seat belt buckle. I didn't feel that this was an appropriate long term solution and I started researching recommended car seats or other workarounds from other Model S owners. I have found several references that the seat belt extenders are not a viable or approved option due to safety concerns, as my understanding is there intended use is for individuals that are unable to use a traditional seat belt. This took them out of the running for me. In the reviews that I read, I found that the Recaro Performance booster seat had multiple recommendations. After much debate, I decided to purchased one with the idea that I would return if it didn't live up to the recommendations. I received it today and installed it to find that this is a great solution to the design of the Model S backseat. The Recaro booster seat footprint is small enough to rest within the seat allowing for just enough room to use the associated seat belt buckle, thus rendering all of the seat belt buckles usable in the back seat. The bonus of the Recaro is that the seat itself is well cushioned and extremely comfortable for my 4 year old. He was super excited that he could un-clip his seat belt, like he can in the other cars all by himself. Additionally, I also purchased the Diono "Grip It" which has proven to be a great compliment to the Recaro. I was previously using the Prince Lionheart 2 Stage Seatsaver and found it to be too rigid for the Model S. Total cost of purchase was approximately $109 on Amazon, both items have the fit and feel of products costing much more. I hope this helps and please let me know if you have any questions about my experience.