As some background, my first Tesla was my white Model X P90D that I picked up on March 26th and put 1500 miles on. I had never test driven a Tesla before and the only other experience I've had with a BEV/HEV was a test drive in a Ford Focus and a short drive in a Prius. My Model X was picked up by trailer to be taken to the Cleveland service center since to get the third row replaced. We don't have a service center in Michigan and a ranger swap out option wasn't offered. The exchange was scheduled a week prior and today they dropped off a red multi-coat Model S P90D with about 5000 miles on it. After a walk around on both vehicles to note any damage, I handed over my Model X fob for the Model S fob, and will drive it for the next three days. I'm expected to have my Model X back on Friday 13th in the afternoon. Here are my observations so far after a 60 mile commute. Interior: The seats are a little more firm but I don't know if it's because of the seat design or the lack of perforated leather. Just as comfortable. All the controls and screens are nearly identical, with the exception of the door control menu, and the addition of the "ionizer" option for climate control. I'm more bothered by the windshield than I though I would be. Without the huge Model X windshield, it feels like I'm wearing a baseball cap, and the brim of the hat is pulled down to block my upward peripheral vision. I had both cars set to auto climate and realize how much smell the Model X filters block out. Today was the first time smelling the diesel truck exhaust in over a month. I put our twins car seats in. I'm really missing the Falcon Wing doors. The elbow rests in the Model S don't feel as far apart as the Model X. When I'm driving my Model X, it feels like I have to extend my elbows a bit to rest on both sides. The Model S feels a bit closer, so I don't feel like I'm chicken winging as much. I hit my hand on the ceiling of the Model S when I scratched my head. The rear middle seat head rest still obstructs some of the rear view, but not nearly as much as the Model X. In the Model S, I can at least see the car behind me without shifting side to side. Exterior: The multi coat red Model S definitely got more glances than the white Model X. Through my polarized sunglasses, the front windshield had a golden hue to it and the side windows had a gray or blue hue. Not sure what that's about and I don't notice a difference in the Model X. I've become too accustomed to auto opening doors and it feels odd having to swing so far out to open the door with my hand; at least there's walk away locking still. The pop out door handles are neat, but again, I miss my auto opening door. The car sits way low and the driver side door opening feels smaller than the Model X, so it's harder to get in and out of. Driving: Seeing the hood while driving is different, I can't see my Model X hood from the drivers seat. The front motor makes a very slight high pitched whine when under acceleration. It's not present while cruising and I don't observe the same sound in the Model X. Acceleration feels the same. Both X and S are P90D insane mode. The loaner Model S is speed limited to 80 mph, but it's not in valet mode. Just an interesting thing. Auto pilot feels the same. I felt more confident taking turns and curves at a faster speed in the Model S. It could be because of a difference in height. Both S and X have air suspension. The regenerative braking on the Model S doesn't seem to slow the vehicle as aggressively as the Model X at speeds under 25 (coming to a stop). It's probably because of the difference in vehicle weight, but it also might be because of the wheel difference. Even though the range is similar, seeing under 350 Watts/mile for 15 miles is pretty reassuring. I've never had a red car before, so if feels super flashy. I'll enjoy driving the Model S for a few days but I'll be happy to get my Model X back.