Automobile manufacturers are producing more eco-friendly cars and trucks these days. Most options you will see available in the US market are hybrids, however, there has been a slow exposure to a second option – clean diesel – brought to you by the European car makers. These two designs of eco-cars are both beneficial to the environment. The Toyota Prius reigns supreme in the hybrid sector and the Volkswagen Jetta TDI is working itself into a very competitive market and makes for a great comparison. Both the Prius and the Jetta are great compact sedans that offer different technologies to buyers who are in the market for an eco-friendly car. Looking at their combined fuel economy and emissions, their performance and comfort, and their overall value, a buyer can better decide which direction to go for their next “green car” purchase.

The technology that powers the Toyota Prius is the hybrid method (dubbed by Toyota as their “Hybrid Synergy Drive” system). This technology allows for the simultaneous use or independent use of two separate power plants. The first power plant, a 1.8 liter VVT-i (variable-valve timing), 4-cylinder, gasoline engine produces 98 horsepower. The second power plant comes in the form of a 650-volt Nickel-Metal Hydride (Ni-MH) battery-powered electric motor capable of producing 36 horsepower, and when combined with the gas motor, they produce 134 horsepower. The Hybrid Synergy Drive system allows the gas engine to be used during high acceleration or during high speed travel independently, while the electric motor can be used for the slower in-town driving entirely or can assist the gas motor when needed. This system greatly improves the gas efficiency and keeps the emissions very low. The Prius is capable of getting 51 MPG zipping through the city and 48 MPG for highway travel, while only emitting 8,688 lbs of CO2 a year during an easily driven 15,000 miles of use and only expect to pay an annual cost of $819 in fuel.

As far as performance goes, don’t expect a miracle. However, by hybrid standards the acceleration is not that bad. The Prius is capable of getting you from a stand-still to 60 mph in 9.2 seconds. Not sports-car fast, but remember this is a green, gas-sipping compact sedan. Couple that with the independent suspension and you are in for a very enjoyable ride. The interior is very spacious for a compact car as well. The Prius seats 5 and has an interior passenger volume of 93.7 cubic feet. The cargo capacity will allow up to 21.6 cubic feet for those long trips or busy supermarket days.

Some may expect hybrid car’s to have a high MSRP, but the entry cost of the Prius is surprisingly low. The starting MSRP for the Prius is $22,800. Add on some high-tech options like solar powered ventilation, collision detection and GPS navigation and the cost can jump to well over $28,000. Toyota will also back your purchase with a 3-year/36,000 mile bumper to bumper warranty, a 6-year/60,000 mile powertrain warranty along with an 8-year/80,000 mile warranty for hybrid component systems. Now on to the competition.

The Volkswagen Jetta TDI implores a completely different type of technology, a turbo direct injection (TDI) diesel engine that produces 140 horsepower and a staggering 236 lb-ft of torque. Now, this diesel engine is mechanically no different than other diesel engines except for the fact that it is capable of using Ultra-Low Sulfur Diesel (ULSD). This cleaner diesel fuel contains lower sulfur amounts than the previous diesel fuel of the past. In fact, ULSD contains 97% less sulfur than the older standard of diesel contained (15 ppm vs. 500 ppm). This new standard was to be fully implemented in the United States by 2010 by all fuel stations and refineries and is mandated by law. The use of ULSD allows the Jetta TDI to implement pollution technologies that will filter out the other emissions that come from the burning of the diesel.

Since the Jetta takes advantage of the technology it uses to lower emissions, the fuel economy of the car is improved as well. This diesel sedan can get 30 MPG in town driving and 42 MPG on the highway. In a year, driving 15,000 miles, the Jetta TDI outputs 10,717 lbs of CO2 and will run you about $1,314 in fuel cost. The optional 6-speed manual transmission or 6-speed automatic sport-shift transmission make the Jetta sportier and more fun for the driver. These options also allow the Jetta to edge out the Prius in the 0-60 stat by 1 second or so at 8.2 seconds. The Jetta’s cabin can seat 5 as well, but lacks in the interior volume compared to the Prius, only providing 91 cubic feet of space for it’s passengers. The cargo space is also less coming in at a mere 16 cubic feet.

A clean diesel Jetta TDI will cost you a minimum MSRP of $22,830. The high-tech features for the Jetta pale in comparison to the Prius, however, premium options such as GPS navigation, chrome side mirrors, body kits as well as larger alloy wheels can take you well over $27,000. Volkswagen will back your Jetta for 3-years/36,000 miles bumper-bumper, a powertrain warranty of 6-years/60,000 miles and they top it off with a no-cost scheduled maintenance of the Jetta for 3-year/36,000 mile coverage.

Ultimately, if you are buying the car for an eco-friendly purchase, the Prius is still on top. In the world of green automobiles, gas mileage and CO2 emissions is king, and the Prius delivers on all fronts. Despite the sportier advantage the Jetta TDI offers, it is still far from the best choice of these two green cars. The clean diesel vehicles have not yet become competitive enough to win this battle, however, word of a Mini Cooper D coming to the United States is starting to take wind and is getting 72 MPG in Europe, but we shall see. Either way, a clean diesel or a hybrid vehicle are a much better alternative to a standard gasoline vehicle if you are trying to buy “green”.