Here's a write-up I did of my comparison (for my purposes, which may not match yours) of the available information on Model S vs. Model X vs. plug-in hybrid Volvo XC90 a few weeks ago:
Tesla Model S, without jump seats in the back: This is a big, 5-seat sedan. With the panoramic roof option, there's lots of space in the front seats. (Without, I'm too tall, so it's a little uncomfortable--this is true for many cars.) The back seats have a fair amount of space--3 big adults across would be very tight, although possible for short trips. I bet one adult, one young teen, and one child would be okay, which means that it would be pretty good throughout the likely usage life-time. (If we have to get a new car in 9 or 10 years, that's fine.) Has a great short-trip range (over 200 miles), and can be used for long-distance travel with free recharging on the road... but the network of Superchargers still has some serious problems (most notably the long barren stretch of I-80 in Pennsylvania, for our purposes), so we would often need to take a meaningfully longer route (say a 14 hour drive instead of a 12 hour drive) with lots of reasonable (half hour ish) stops to recharge along the way--it could easily add several hours of total travel time to a 12 hour trip. Available in all-wheel drive. Excellent safety--good but not necessarily best around crash avoidance (Autonomous Emergency Braking system, adaptive cruise control, lane departure warning, good camera system, inconveniently located but present blind-spot warning), excellent crash test results, ridiculously good avoidance of roll-overs, excellent subjective crash avoidance handling in Consumers Reports testing. Also extraordinarily expensive (roughly twice the cost of the Ford Fusion Energi, three times the cost of some of the small cars), but within the range that we could afford, although it would certainly bite into the money we have for other things. Has a very high awesome factor.
Tesla Model S, with jump seats in the back: this adds two small rear-facing child seats in the hatchback area. The upside is that, while the kids are small enough to use them, a seating pattern like 2-2-1 or 2-2-2 is likely to be very comfortable. It also makes guests feasible (say, an adult friend, their child, and our whole family all fitting in the car at once) Downsides: less storage space even when folded up; we'd probably need an external storage pod on the roof for long-distance travel with the seats in use, which has efficiency costs and adds extra expense; some kids get motion sickness when facing backwards; some reports that those seats can get very (perhaps dangerously?) hot. Otherwise, the same as the Tesla Model S without jump seats.
Tesla Model X: We don't have full details on this yet, but it's a roomier, bigger Model S. It would cost a little more, but frankly, an extra $5000 of cost isn't likely to break the bank. Somewhat less efficient than the Model S (maybe 10% less efficiency and range at a given point). Should have lots of space--7 adult seats (2-3-2), where 2-2-2 should be very comfortable and 2-3-2 may still be comfortable. All wheel drive standard. Safety information not available yet. (ETA: Tesla says internal safety testing shows extraordinarily good safety results, but no external crash test data is available yet.) We would probably get a delivery in the first half of 2016, which is late but would be okay--but the delivery could be delayed. New orders are looking at the second half of 2016. I expect it to be comparably safe to the Model S, but perhaps less so because of higher center of gravity (but perhaps not meaningfully so, because the battery pack is still most of the weight and evenly distributed around the bottom of the vehicle).
Volvo XC90 plug-in hybrid SUV: This is a mid-sized luxury SUV (i.e. a very large vehicle) that is a plug-in hybrid. It's supposed to have an all electric range of 25 miles or so. It looks like it may have anemic power in all electric mode given the size of the vehicle--I don't need the (stupidly good) acceleration of the Model S, but I'd rather not have worse acceleration than my current Prius. An 87 horsepower electric motor is not a lot to move a 5000 lb. vehicle. It seats 7 adults--probably quite comparable in space to the Model X, but perhaps a little roomier. It's not clear how efficient it is in EV mode. Some reports suggest 59 mpge, which isn't very good, but some claim in the ballpark of 100 mpge, which is comparable to the Tesla Model S. Official numbers aren't out yet. It's basically not available yet, but supposed to be available real soon now--I view it as comparable to the Model X in this regard, but it might have a faster progression to wide availability. It has probably the best crash avoidance technology of any vehicle I've looked at, and the ICE version does extremely well on crash tests (better than the Model S in some regards, at least in the European crash tests), but it gets good but not great marks on roll-over avoidance (it's a top-heavy SUV, after all). It is a gas guzzler in non-EV mode--with the ICE providing the power, it gets about 25 mpg highway, 20 mpg city, which is pretty terrible. It's a little cheaper than the Tesla (probably 10% cheaper in the configuration we'd get, although maybe a little less once tax incentives are taken into account), but in the same ballpark--my belief is that the total cost of ownership, counting gas for long road trips, would be a little higher than the Tesla. All wheel drive is standard--I'm not sure if it can do all wheel drive in EV mode, though, so that may require using the ICE when driving around in snowy conditions.
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My take away is that the Volvo XC90 hybrid probably is much less green than it appears to be. I suspect, but we'll need to do a test drive to confirm, that the electric mode is very hard to use for routine travel, so even driving a local commute is probably often going to involve some gas usage. And the ICE is not efficient, so if it kicks in to add acceleration or to go up a hill, the overall efficiency probably drops a lot. Plus, any long-range travel will be very inefficient, running around 25 MPG. If I can test-drive a XC90 hybrid, I will do so, but I currently think it's entirely the wrong car for me.
