When you brought up this
When you brought up this story and we talked about it, I was actually rooting for the diesel, but I knew it would be close. With the Passat TDI vs Volt, the real killer was the purchase price. The Volt beats the TDI in markets where state incentives might add half again the federal incentive ($7,500). With the Jetta, the price difference is only a couple of thousand, so for the hybrid to make up for that, it wouldn't take a lot of efficiency gains to offset that difference.
Of course, many readers who left comments on my comparison did just like the guy above and attempted to use non-scientific, "real world" numbers to bolster their preconceived notions.