Edmunds did a study that showed diesel purchasers recoup their investment in a diesel engine much faster than those who pick a hybrid engine instead. In fact, the Mercedes S-Class diesel returns the engine investment in under a year! And this, of course, doesn't take into account that diesel engines are made for longevity and should outlast a hybrid by a fairly large margin. And, of course, if you run the engine on biodiesel, it's waaaay cleaner.

We welcome you to discuss the difference between diesels and hybrids in the diesel vehicle section of our forums.
 

Edmunds Data Proves Diesel "Break-Even" Is Shorter Than Hybrids
By Philip Reed, Senior Consumer Advice Editor
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This monthly column presents crucial, stand-alone car-buying strategies to help you avoid dealership tricks and traps and get the best price on your next car or truck.

With a new crop of diesel vehicles poised to invade the U.S., Edmunds.com has discovered that diesels present an even better choice for fuel-economy-minded consumers than hybrids.

Diesels cost more than their gas-powered equivalent vehicles, but this higher purchase price is quickly offset by fuel-economy savings. With hybrid vehicles, this so-called break-even period is longer — in some cases as much as eight years longer.

With high fuel prices, consumers are steering their car purchases toward vehicles that get better fuel economy. For many shoppers, this means their first thought is to buy a hybrid vehicle. But in light of this new data, they should also consider a diesel vehicle, said Alex Rosten, Edmunds.com analyst.

"Diesel engines produce a greater fuel-economy boost over their gasoline counterparts than do most hybrid powertrains," said Rosten. "This makes it a great choice for anyone tired of rising oil prices."

Case in point: The Mercedes-Benz M-Class diesel costs more to buy than its gas-powered counterpart, but the improved fuel economy it delivers pays for this higher cost differential in only 2.1 years. Compare this to the scenario where a car shopper chooses the Lexus RX 400h (hybrid) over the Lexus RX 350 gas-powered car. In that case the better fuel economy of the RX 400h takes 10.2 years to pay for the cost difference (see chart below).

In another example, the Jeep Grand Cherokee with a diesel engine gets 27.3 percent better fuel economy than its gas counterpart. This saves $785 a year in fuel costs and pays for the higher-priced Cherokee in 3.1 years.

Turning to hybrids, the Toyota Highlander Hybrid only saves $455 a year in gas and thus takes 6.5 years to justify its extra cost.

So if diesels are so thrifty, why don't more people choose them?

"In the past, diesels have gotten a bad rap in this country," said Director of Vehicle Testing Dan Edmunds. "The diesels that were sold here were slow, noisy and smelly. But all that's about to change."

Breakthroughs in diesel technology by Honda will mean that they can again be sold in states with tough air quality restrictions. The new diesels, with impressive fuel-economy benefits, may steal some of the fuel-economy market share from hybrids.

Additionally, diesels are a good option for consumers who want to cut their use of foreign oil and show their support for energy independence. Diesels can run on biodiesel, produced in the U.S. from crops such as soybeans, with little or no modification. Biodiesel is often more expensive than "petro-diesel" but there is little drop-off in fuel economy between the petroleum-based fuel and the biofuel. This is not the case with E85 (85 percent ethanol and 15 percent gasoline), which costs less to buy but because of a steep decline in fuel economy is ultimately more expensive to operate.

"Another point in diesel's favor is that it offers a better 'well-to-wheels picture than a gasoline-powered car,'" said Edmunds, referring to the entire environmental impact of drilling, refining and shipping the fuel to the filling station. "Diesel requires less energy to refine and then provides more fuel economy when it's burned — that's a double win for environmentally minded consumers."

There are, however, drawbacks to diesel vehicles, Rosten cautioned. Few models are currently available and new diesels are not sold at all in five states — California, Maine, Massachusetts, New York and Vermont. The 2008 Chrysler, Mercedes-Benz and Volkswagen diesels are expected to be legal in all 50 states.

Still, many experts believe that the benefits far outweigh the drawbacks. And for anyone looking for a new option to hybrids, diesels are definitely worth consideration. Eventually diesels will be combined with hybrid powertrains, making it the best of both worlds.

Here's a quick look at some 2007 diesels and their payback periods as compared to the break-even period of some hybrids:

Make	Model	TMV	Alt. Fuel Premium	Combined MPG	Mileage gain vs. gas engine	Annual Gas Savings	Years to break-even
Mercedes-Benz	E-Class diesel	$50,248	$294	32.0	35.2%	$595	0.5
Lexus	GS 450h hybrid	$53,390	$520	27.0	19.3%	$329	1.6
Mercedes-Benz	M-Class diesel	$42,764	$1,298	25.0	27.1%	$616	2.1
Lexus	RX 400h hybrid	$39,991	$4,334	29.7	27.5%	$426	10.2
Jeep	Grand Cherokee diesel	$31,642	$2,534	23.3	27.3%	$663	3.8
Toyota	Highlander Hybrid	$31,449	$2,954	29.7	29.4%	$455	6.5