Yeah, you're right, there are other factors like maintenance etc. Just plug your numbers into my calculations. You'll obviously hit the break even a lot sooner if you're filling up x2/week, but if you have to spend $5k for the car, you're talking a lot later break even point.. Don't forget to add the insurance for the 2nd car.
But there's an intangible figure here too, that you can't put a dollar figure on. It's exactly what you said, seeing the mileage add up on the VX.So a 2nd car IS worth it in some scenarios and it's not related to fuel costs at all.