Twin-Air.
I had a TA 500 hire car too a couple of years back whilst mine was in the garage. I liked the looks, liked the Stop-Start too, but the little engine just ran out of steam getting up the long hill westbound on the M62 past Brighouse, and there was only me in the car.
I love the idea and the tech behind these little turbo engines, but sometimes there's just no substitute for cubes!