- Front "Comfort" seats on X5 are more adjustable (back has a pivot point so that shoulders are adjustable separately from back angle). For short drives, we were comfortable in Model S, but obviously don't know about long drives. Some seat positions on Model S have the driver's head too close to the headliner, which is a really claustrophobic feeling.
- Rear seat on Model S is too low so your knees stick up uncomfortably even on short drives; headroom is marginally OK. Agree with Robert that center seat in Model S is better than center in BMW, but that's the least used seat of all.
- Rear of X5 has slide out cupholders for passengers. Model S has none.
- All 4 doors of X5 have deep, very usable pockets. Model S has none.
- It's shocking that the gas car has more power ports than the electric car. Tesla should be ashamed. There is no excuse for Model S not having 110 volt outlets in the back, and there should be power available in the frunk and/or rear cargo area to run a cooler.
- X5 has a true panoramic sunroof that makes Tesla's claims about Model S's laughable. And the X5 shade is powered. And vent mode pops rear of both glass plates.
- Rear cargo on Model S is better than X5. Frunk is huge bonus.
- Suspension & driving: Model S wins big (the most important aspect for many).
- Maintenance: This is our second X5. Our first had some weird engine (6 cyl 3.0L) problem that BMW couldn't solve. Heard that BMW was going iDrive, so when we got a good price for it we ordered the 8 cyl version (last without iDrive) with the specific options we wanted to replace it. The new one had software transmission issues that took BMW months to solve. It's still a little jerky if the road slope and car speed are just so. Unknown what Model S will be. I have some concern over PEM repair costs years down the road.
- Options: When we got our second X5, we optioned it exactly as we wanted. Heated steering wheel & rear seats. Dark headliner, burl wood and black leather. Sport suspension & steering wheel, but with Comfort seats. The interior is subtle and comfortable and is high quality (has held up very well over 7 years and 105K miles) without feeling overly luxurious, if you know what I mean. My wife loves this car and feels extremely comfortable driving it, including its high driver position to see over traffic.
- Model S is going to be a mixed bag with options/technology/luxury: The touchscreen is outstanding and revolutionary, it has a rear view camera whose view is large enough to actually use, yet it lacks rudimentary park distance sensors and for such a wide car to not have electric folding mirrors is going to be a little scary at times. I appreciate the spartan, open interior of Model S, but on the test drive my wife insisted on putting her big pursebag in the back seat, even after I suggested otherwise! That you can only get the headliner in beige is disappointing, especially with the black bar across the sunroof, which ruins the effect for rear passengers. I'd rather save money and just have a normal sunroof that slides inside the roof so has less drag, less exposure when open. Tech package has some cool things, the ambient lighting inside should be very nice during night drives, but the exterior handles are just silly and impractical. Hopefully the tech package will make them not annoying, but this is an area of concern for us.
- Steering wheel & controls. The BMW just nails it here. The Mercedes-derived Model S controls are lame in comparison and swapped turn/cruise control stalks are simply inexcusable: I used to think Mercedes drivers were not courteous, but now I know it's that they've given up trying to find the turn stalk.
It's fair to say that if Model S wasn't electric, we wouldn't be buying it. Tesla's electric drive and air suspension are huge pluses, and are the reason we're willing to overlook its shortcomings in other areas, but to be honest, the decision to buy/not buy in the end was close (I started a thread on Second Thoughts to explore it). If we needed rear seats on a regular basis for adults we would have cancelled/change to Model X. I do expect Tesla to continuously improve Model S. We are likely to either retrofit whatever new things are available and/or trade in for V2 when it comes out (like some Roadster owners did with their 1.5s when 2.5 came out). I agree with Tesla's decision to concentrate on the drivetrain, since that has to be right for them to be successful (look at Fisker's decision the other way for comparison), but that doesn't mean I'm going to cut them continual slack on making MSP worth $100K or Musk's claim that it's the best sedan in the world.
While I'm on the soapbox, Tesla needs to think about what is the best form factor for electric cars. Making cars that look like they have engines up front may be what people want today, but that's like early automobiles looking like carriages without the horse - something that won't last. Tesla needs to think about what losing 5-6" of height to batteries in the chassis does to occupant comfort. My personal view is that they should have laid the batteries on their side in the chassis so that the height loss might only be an inch instead of 4-5, and for the batteries that wouldn't fit they could put some in the back part of the frunk and the rest in a normal center console.