I'll jump in here. I have a Jetta Sportwagen TDI (which I love, but apparently not as much as VW loves it since they're giving me a nice chunk of change for it). The A3 has always been on my radar since it's similar to the Sportwagen.
This go around, I was looking at a variety of cars. Drove the Volt and was impressed with it, but in the end, it was just a little too small. Only seats 4 (unless the 5th is a car seat), and the trunk space is very limited. Also, the one I looked at was only a $1-2k less than a Premium Plus e-tron. Audi was willing to deal, and Chevy wasn't.
The e-tron has basically the same interior volume as the Sportwagen, so I'm not losing anything there. Cargo space is less, but still seems usable.
As Arne said, the Audi is a nice step up compared to my Sportwagen (wife has the Jetta sedan) and to the Volt. Quieter, more solid, sporty drive when you want it. My daily commute is ~5 miles each way. Add in lunch out each day and I'm still driving on battery alone pretty much every day. I get ~15-20 miles pure electric (probably closer to 20). Even on the weekends, I'm usually driving less than 20 miles per day. Where my miles get added is on the road a few times a year (~1200 mile trips to family). On those trips, the difference between a Volt and my e-tron is minimal as both are going to be mainly hybrid. I picked up this car in San Antonio so I had a couple of trips back/forth already. Even with those trips adding 750 highway miles, my first two tanks were 60 mpg and 47.5 mpg. Best I ever got in my Sportwagen was 38mpg. I suspect now that I'm on my normal driving routine, I'll get 70-80 mpg tanks easily, if not better. The main enemy to my gas mileage is me. I occasionally can't resist the urge to drive in a "spirited manner".
Naturally, I think my new car is better than my old car, but my teenage daughter, and my wife both offered unsolicited opinions that the Audi is much nicer than my VW. The TDIs are nice but we all know where that ended up. This e-tron seems like a nice replacement.