Good deal. I hate vehicles that won't start. The coldest my IDI started at was -3F after an overnight soak, and it started really quick. I had a brand new injection pump and injectors, new glowplugs with manual control, decent group 65 batteries and cables, a good starter, and proper timing. The when I moved to Arizona it was a pain to start anywhere under 30, even with brand new group 31 and brand new battery cables including a 3/0 lead to the starter. I think the elevation had the most effect, and the fact that the IP was no longer brand new but had 10k or so on it.
My Jetta TDI starts really well generally. I run 5W40 synthetic in it all the time. The coldest I've needed to start it was -15F, at 7000 ft elevation, and it was hard. It did start, but took more cranking than I like. I went through the 12/13 winter driving it daily with no block heater. I'll never do that again. Now I have a garage attached to the house, so it stays reasonably warm so I don't need a block heater anyway. Just have to make sure that I run fuel additive - it could start up fine in a 30 F garage and gel up running down the highway at -10 F.