Chevy Aveo or a Smart, I personally would go with a Smart if i could find it but the Aveo has great gas mileage and is still ver cheap.
'smart' require premium and is about as impractical as a car can get. High center of balance plus narrow track=very unstable. Fact is that a 70s Porsche 4 cyl... 912, 914, and a handful of 356 with type 4 in 'em get better mileage than a 'smart' when they are tuned correctly... There are plenty of 1.7 Type 4's in the 40+ mpg range... Hell of an improvement in 30+ years? As for the Aveo's... while I've never personally known anything to be wrong with them, the fact is they are fairly hit and miss and for their size the mileage isn't upto par. So as to best bang for your buck...I understand the VW Jetta diesels are the most cost effective. They are large and powerful enough to be practical, and many drivers claim in excess of 40 mpg... granted the EPA estimate is in the mid to low 30s depending on the year. I personally am waiting for the Loremo to go into production and sales in the US before purchasing my next car... The Loremo LT is a bit too slow to be safe for highway driving... Small car merging below speed of traffic=not a great idea (20s 0-60 eek...). However, the Loremo GT looks to be promising... 80+mpg and a 0-60 under 10s... Just a few more years...