Purchasing a car is likely the second largest investment you will make – and one that you will likely have to live with for at least the next few years – so you want to make the best, cleanest, most fuel efficient, safest, and cost effective decision. For my husband and I this decision has lead us beyond the land of hybrid vehicles and into the land of diesel engines.

The 2009 Green Car of the Year award went to a Turbo Diesel Injected (TDI) vehicle – the Volkswagen Jetta Clean Diesel (TDI). This is the first time the award has gone to a clean diesel vehicle. For Americans, a diesel car probably sounds like an old, dirty engine, but its time for all of us to get back on the diesel bandwagon. Europeans have been driving these new diesels for years, but these cars have only recently been able to meet the stringent American emissions standards. In fact while adventuring to Copenhagen, Denmark, it was hard not to see one of these (or the wagon version) cars on the street — even as taxi cabs!

Hands down, this is a performance vehicle. Its powerful, even though it is only a four cylinder vehicle. Because my husband and I have been seeking a car that would allow us to become a one car family and yet still have plenty of space for lugging things home, someday growing a family, and hopefully space for a dog, we looked at the sportwagon version of the VW TDI. Testing driving this car, we were nearly sold, but it was the little bonuses for the price that really sealed the deal. This car has gadgets galore — and most of them are standard! Between the Bluetooth (which even allows you to play music over the speakers that is streamed from your iPhone), the touch screen radio, and the digital dashboard readouts, this car has just about everything a geek could want! Further, the seats fold down perfectly flat, the front seats (and back!) are heated, and the side view mirrors have a defrosting option. All around, this car is fun to drive.

Its not all fun and games in these cars though. Some of the toys genuinely help the driver drive more efficiently. Much like the Ford and the Toyota hybrids which display the fuel efficiency of the car, the VW and Audi clean diesel cars show the average fuel economy for your current driving trip and your tank of fuel. They also show you instant fuel economy based on the speed you are traveling. These gauges help drivers learn which driving styles generate the best fuel efficiency for the vehicle. Of course, also like most of the hybrids, most clean diesel cars also offer built in navigation which can also help you increase your fuel economy by showing you the most efficient way to get from place to place.

But what’s so great about the clean diesel technology and how is it different today than it was years ago? First of all, today’s diesel engines are highly efficient. The VW Jetta Sportswagon, for example, gets 30mpg in the city and 41mpg on the highway. Best yet, these mpg stats are likely to be surpassed. (It is a Jetta TDI that currently holds the world record for best fuel efficiency with 67.1mpg.) With 236 foot pounds of torque, this vehicle is powerful to say the least, able to move quickly from a standing start and pass other moving cars with a light tap of the petal. In comparison, old diesel engines were known for being loud, hard to start, and belching smoke, a far cry from these clean engines, even if they were efficient for its time. With prices for diesel fuel not much more than that of gasoline and the prices staying far more steady, its no wonder why Americans are beginning to again look towards these new technologies.

Interestingly, the Audi A3 clean diesel TDI is the 2010 Green Car of they year. This makes two years running for a clean diesel cars to win the coveted award.

So if you are wondering what it is my husband and I purchased… you guessed right! The VW Jetta Sportswagon TDI. We call her “Gretta the Jetta.”