I've had a Toyota Yaris Verso now for 2 years now, and it's the roomiest and most reliable car I've ever owned. I find it gets about 45 miles per gallon (a bit less in the city), and there's a handy range-o-meter to show exactly how much juice it's got left. Mine is almost 10 years old but still doing wonderfully. It sailed through two MoTs, just an advisory about the exhaust.
Reasonably cheap to insure as well, cost me about £450 a year with Direct Line for fully comp and my other half named on the policy.
The best thing by far is the ENORMOUS amount of space inside. I can fit my family of five comfortably inside, and enough luggage for a weekend away. It is just the perfect family car: all the space of a people carrier, all the economy of a small hatchback. The rear seats can collapse down and disappear underneath the front seats too; we've had 4 bikes in there before. The rails on the roof of the Yaris Verso make for even more storage space.
I've only marked down the handling because it's a tiny bit wobbly in high winds, but it's a tall car so that's to be expected; and the performance because, well, it's hardly a Porsche!