I own an MK4 Jetta, but I think this could apply to other models as well. I live in Winnipeg, Canada so this is for people who live in similar cold weather climates like mine. I have owned a 1991 diesel and traded up to the 2001 one I have now. Cold weather starting with the VW diesels I've owned has always been easy...as long as you have the battery power. At -35c the battery is down to about 15-20% of full. Turn on the key to activate the glow plugs and poof, there goes the rest of the battery power leaving little to nothing to turn the engine over. To counteract this, for years I'd run a "battey blanket" that surrounded the battery and plugged in to ac (80 watts). As you can imagine, it's difficult to apply and still maintain the battery cover. Last year I decided to drop this in favour of a small battery maintainer (2 amp) normally used to keep up batteries in off season vehicles like motor cycles, ATVs, snow mobiles, etc. The cost was $19 and came with several different hook ups. I used the ones that connect straight to the battery cables, hopefully you can tell in the pics. I mounted the charger to the firewall area, and the ac plug "Y"s into a cord where my oil pan heater also connects so I just have one cord to plug into a receptacle. Obviously this is for places you park that have ac for winter plug ins. It worked absolutely great all last winter keeping the battery maintained through the day at work, or at night at home. Lots of power for starting everytime. Thanks for reading, hope someone gets some use out of this post.