1) He never mentioned shit about roominess, just mileage.
2) The Yaris makes way more sense: If he's driving 30K miles a year and it's going to take him 7 years to break even, then there's a slight problem. The battery has an 8 year/100,000 mile warranty, which means that he's out of warranty in year 3.5, or 3.5 years before breakeven.
3) New Yaris in year 5 for trade-in vs a Prius with a battery that has 7*30,000=210,000 miles on it. I know which one is going to have higher value and it's not the Prius.
Summary:
-He's going to be out of warranty in year 3.5 on the battery
-Even if he makes it to breakeven point in year 7, less trade-in value at 210,000 miles vs 5 year old Yaris with 60K miles. In fact, the Yaris is worth almost twice as much (Source: Autotrader 2005 Prius vs 2007 Yaris), 7K~ vs 13.5K~.
-More than 10% horsepower for passing with the Yaris, which could increase even more as tech increases in the 2 year gap.