It doesn’t make sense to condemn an apple for not being as good as an orange or vice versa. They are both fruits that essentially perform the same function but appeal to different tastes and provide some different benefits. Just as it is unreasonable to compare apples with oranges, it is unreasonable to fault hybrid technology for lacking certain characteristics found in non-hybrid diesel engines and vice versa. However, what will be interesting is to observe how diesel electric hybrid technology will evolve into the market, which may allow consumers to get the best of both worlds or very close.

A diesel BMW 520d was compared with a Toyota Prius in a European road test. The diesel BMW got slightly better fuel mileage at 50.3 mpg while the Toyota Prius achieved 48.1 mpg. To me the comparison is very interesting because it illustrates how the Europeans have embraced diesel engines and how high energy prices have brought efficiency much earlier there than here in America. However, I believe the comparison is like comparing apples with oranges.

Diesel engines
According to Wikipedia, what makes petroleum diesel attractive over gasoline is “the higher energy per-litre content of diesel fuel, reduced maintenance costs due to fewer parts and longer engine life, and the intrinsic efficiency of the diesel engine.” In addition, diesel engines are even more attractive because a standard petroleum diesel engine can burn biodiesel too. Furthermore, a standard diesel engine can be modified to burn vegetable oil. However, both diesel and biodiesel emit smog-forming nitrogen oxides so it does not make sense to use diesel engines in cities when hybrid technology can help remedy the problem of smog pollution. Furthermore, the stop and go driving associated with the city or commuting into cities makes non-hybrid diesel engines even less efficient than hybrid technology.

Hybrid batteries
Despite what people erroneously claim about the longevity and recyclability of hybrid batteries and their impact on the environment the Prius and other full hybrids are just as good as a non-hybrid diesel engine if not better in my opinion. It is not as if the consumer will toss the battery in the trash because of bounties and laws regulating car battery disposal. Furthermore, everywhere I have purchased a non-hybrid replacement battery they are kept and recycled. The same policy is true for hybrid batteries although hybrid batteries are made to last the lifetime of the car. However, like most parts on a car, unreasonable use can result in early and unnecessary wear of car parts like engines and transmissions much faster than normal.

The versatility of a Prius and other full hybrids
Perhaps what makes full hybrids superior to non-hybrids is their superior versatility and utility. For example, the Prius and other full hybrids can be converted into a PHEV (and get over 100 mpg), integrated with solar to recharge the battery and used as a backup home generator. Many drivers get much better mileage than 48.1 mpg from a standard Prius too. I believe both clean diesel, biodiesel, flex-fuel vehicles and hybrids are needed and these choices will continue to evolve. I agree with this comment from AutoblogGreen:

Why should one directly compare diesels and hybrids? Both excel in completely different usage scenarios. Diesels win on typical long and smooth commutes with relative few stop-and-go situations. In city traffic, they are sometimes even worse because of the heavier weight. Hybrids can score in typical traffic jam, short commutes or stop and go traffic in the cities. Besides that, regarding NOx it makes more sense to use hybrids in the city.

Of course a comparison could tell you exact numbers, how many miles per year make diesels more efficient and what percentage of city traffic makes hybrids better. And yes, diesel hybrids would combine both advantages, but they would alos [sic] combine both premium prices.

1. On the Net: Tank vs. Hybrid – Is it possible that a Hummer’s better for the environment than a Prius is?
2. On the Net: In search of the perfect battery
3. On the Net: About Biodiesel
4. On the Net: How to Use a Toyota Prius As a Backup Generator
5. On the Net: Car That Doubles as a Backup Generator for Your House
6. On the Net: Turn you Toyota Prius into a PHEV now
7. On the Net: Integrate solar power into your Toyota Prius and drive on sunshine

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