New I'd go for a Smart or a Yaris. I'm not a fan of the Fit/Jazz.

Used? VW TDis are inordinately expensive compared to over here so again I'd go along the lines of an Echo. There's a guy in CA imported an Echo HB from Canada a year or so ago and I know he's ordered a new Smart... His Echo is really frugal, a bit different and I could put you in touch if you like.

A