Audi A1 E-tron

This news isn't actually new, but the A8 thread reminded me of this A1 serial plug in hybrid.

Geneva Auto Show: Audi A1 E-tron - NYTimes.com

On a draft European test cycle for plug ins, it gets 124 mpg, but that baby Wankel may not make it to production. Audi wants it for the space savings. VW doesn't want to pay to develop it. Going to Mazda would appear to be the obvious solution, but I doubt they even have something that small. One rotor of the RX-8 engine still has about 2.5 times the displacement.

That aside, I actually posted this because the A1's there are what I consider to be about ideal for a PHV. Some even apply to non plug ins.

A 10 second zero to 60 is plenty for driving on the roads here. Those that complain about it being too slow are really complaining about the acceleration feel, and they likely haven't had a chance to feel the torque from an electric motor.
80mph exceeds the speed limit every where in North America as far as I know. I can see how this might be a concern if it is an actual physical limit of the drive train though.
31 miles electric range would cover half my commute, but there is many variables to balance. Pack cost and fuel economy are the biggest. It will never be one size fits all.
This is the stand out to me, 124 mile range on the fuel tank. It may become bothersome on a road trip, like say, the 600 mile one to my parents. But that's only a few times a year, and I would likely benefit from more breaks to stretch the legs. In day to day driving, this is too short for few people.
Don't get me wrong, going without having to stop for gas for weeks at time does give one a level of satisfaction. Until you start thinking how that excess weight of all that extra fuel might be costing you a tenth of a mpg. I was purposely under filling the Gen2 when I had it because it got better economy around the half tank mark.
Hypermiler issues aside, a smaller tank is a boon to a plug in because of gas aging issues. If the turnover rate is fast enough, the manufacturer won't have to require high octane in response to reliably, customer satisfaction, and warranty concerns. If the fuel still happens to go bad, and requires to be drained, it is less fuel wasted.

One final thing, the question came up in the other thread about the possibility of an Atkinson rotory engine. Apparently it is.
Rotary Engine - White-Smoke

 

Just a little tidbit, the engine on my walk behind mower is 190cc.

 

Speed is likely limited to to keep the EV range reasonable and extend the battery and motor life. It can boost power output by 25% for a short burst

In those areas of Texas with 85mph speed limits, I don't think EVs and PHVs are serious contender with most car buyers. Just going by range logistics.