2010 Volkswagen Jetta TDI Cup Edition: Cold Weather Start
2010 VW Jetta TDI Cup Edition: Cold Weather Start – Click above to watch video after the jump

The 2.0-liter turbo diesel in our long-term 2010 Volkswagen Jetta TDI Cup Edition is a very modern mill, so we were curious how it would handle starting in the frigid clime of northeastern Ohio this time of year.

Diesel engines typically have three vulnerabilities when it comes to cold weather starts: the fuel, the battery and their glow plugs. First, the new Ultra Low Sulfur diesel fuel we all use begins to gel at a higher temperature than the old fuel. Sulfur is also a lubricant, and with less of it, the fuel pump has to work harder in cold temperatures to keep the thicker diesel fuel flowing. Fortunately, most diesel fuel sold in colder areas has ant-gelling additives mixed in already.

Batteries are also less efficient when cold, while at the same time having to work much harder to crank the engine more times. Finally, diesel engines use glow plugs to heat the point of combustion in each cylinder, which is a much tougher job when the mercury drops below freezing. Optional block heaters can help a diesel engine start in cold weather, but Volkswagen has enough faith in its 2.0-liter TDI that it doesn't even offer one.

So how did our Jetta TDI Cup Edition do when being started in 25-degree weather after sitting for over 24 hours? Follow the jump to see for yourself.