Seems like these little tsi engines are great on fuel. Some time ago I had a mk3 Leon with the 1.2tsi and the 1 regret I have when chopping in for the Astra is the fuel economy. Although my 1.6t has quite a bit of get up and go you soon get used to it and the mpg (to be expected) is nowhere near the Leon .I was even tempted to look at the Leon 1.0 115 just after purchasing the astra when the Astra drank a huge amount of fuel in its 1st week ! Size wise though I think the Ibiza is perfect for me and the Mrs. I just got to get down the dealership sometime.
Having had 3 years with each, the 1.2 was a way superior motor compared to the 1.0, having a usable torque band made all the difference.
But you can mask the 1.0 deficiencies by ordering a 7 speed DSG and letting that do all the work.