I've had two cars with pano roofs, seven years worth of owning them, never had a problem. The rest of my cars have had sunroofs. I am tall at 6'1", never noticed an issue with head room (folks taller than me might have issues, I guess).
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My CX-50 (non-turbo) is up to one full year of ownership: 29.7 MPG (all fill ups recorded). My best tank was this summer (going to Acadia, very little highway) at 37.9 MPG. It is EPA rated 24 city, 30 highway, and 27 combined, as I recall. Since April, my worst tank was 29.9 MPG (my most recent tank was 33.9 MPG).
My Civic averaged 37.8 MPG (which is less than its highway EPA, but more than its combined EPA). Given my driving conditions and style, I'd say the CX-50 has really over performed by averaging its highway EPA.
The vehicle is very thirsty off the line, though. Driven in the city, I could see low 20s at best, maybe worse with a heavy foot in the city. The turbo in the city with a heavy foot would never hit 20 MPG, ever.
A hybrid version is due soon, looks like it will have the Rav4 hybrid engine (and a CVT instead of automatic), as anticipated for many years. Same EPA MPG as the Rav4 Hybrid. I wonder if Mazda was able to tune the engine better? The Rav4 hybrid is known as a loud droner (and Mazda is well known for a higher quality engine/product).
The price difference between my ICE version and the hybrid (equivalent trim) is around $5k-6k or so. Given my driving patterns, I would expect worse MPG compared to EPA on the hybrid (which don't do too well in cold NNE winters and on long highway drives to ski areas).
I gave up holding out for the hybrid version. Given the price difference, I don't regret it (especially seeing what looks like the Rav4 engine with a CVT). I think it would be almost a wash in total fuel costs after accounting for the hybrid premium (and I doubt the hybrid version will get discounted for a while).