I've heard a lot of back and forth on this issue, but when purchasing our next vehicle which is actually the better way to go?
For us, we cannot go fully electric at this point due to drive times, and there is no good public transit close to our house.
This questions whether it is environmentally friendly to purchase a new hybrid, but doesn't really address the choice between types of used vehicles: How to determine whether hybrid cars are really better for the environment?
TLDR; In my estimation, a new car never makes sense, from an environmental standpoint. And a hybrid never makes sense--it offers the worst of both worlds (all the pollution, manufacturing, and disposal footprint of internal combustion and electric).
All things considered, the fuel consumption of any vehicle is minor compared to the manufacturing, disposal, and maintenance footprints.
A used vehicle has the lowest manufacturing footprint, sometimes at the cost of greater maintenance footprint.
I have read (disputed) reports that the environmental footprint of a Prius is the same as that of a Hummer after 100,000 miles. True or not, it helps one think about putting fuel consumption into perspective of the larger picture.
Full disclosure: I have owned 6 diesel vehicles. I currently own an '86 TurboDiesel Jetta, and an '03 TDI Jetta. I have never owned a hybrid.
Without any specifics (because I don't know them):
A hybrid vehicle reduces emissions (although in the U.S., the most efficient hybrid is barely more efficient than the most efficient diesel vehicles, in Europe, there are even more efficient diesel vehicles). It increases manufacturing and disposal footprint.
Environmental factors which are roughly the same for both a used biodiesel and new hybrid vehicle:
Factors which are greater for a new hybrid:
Factors which are greater for a used biodiesel vehicle:
*My '03 TDI Jetta gets better fuel economy than all but the newest and smallest hybrids (and it's a lot more fun to drive). All biodiesel is not created equal. If you have a source of biodiesel recycled from used oil, the fuel refinement cost is practically nothing. If you are buying commercial biodiesel in the U.S., it is almost certainly made from soym and onventional soy farming is not sustainable. Although, the most recent numbers from the USDA suggest that soy biodiesel is more efficient than before (thanks @Nate). Although the USDA has a clear bias (an interest in promoting aggriculture), I have no specific reason to think their numbers are wrong.
My suggestion, in order of least environmental impact (assuming you are using the most fuel-efficient vehicle in each class, that will suit your needs):
**I don't actually know if an all-electric vehicle is better than internal combustion, but I suspect it is, because it reduces the mass of the vehicle, and many peripheral fluids (engine coolant, motor oil, etc).
***It's hard to rank hybrids accurately. Some biased sources claim they are devilspawn. Other sources, biased in the other direction, claim they're heaven-sent. The truth is probably somewhere in the middle. So take this absolute raking with a grain of salt.
Also note that even without biodiesel, a diesel vehicle is more sustainable than a gasoline vehicle. All other things equal, diesel gets roughly 33% better fuel economy than gasoline per fuel volume. Diesel refining is also, arguably, less harmful to the environment than gasoline. And lastly, a diesel engine is mechanically simpler than a gasoline engine, and thus will last longer (500k miles is common).
I suggest looking for a good quality used diesel vehicle. A 2000-2003 Jetta TDI is the ideal right now, easily over 50mpg highway. But even the newer Jettas still get excellent fuel economy, and the older ones can, too. My '86 gets about 40mpg. My '03 about 52mpg.
Fuel consumption is typically 70-90% of a vehicle's lifecycle energy consumption and greenhouse gas (GHG) emissions, so there are lots of circumstances where upgrading to a significantly more energy-efficient vehicle makes a lot of sense. See, for details TRL VR6 and The UK Automotive Sector: Toward Sustainability.
If the vehicle being replaced gets a very large proportion of its materials recycled, then that helps even more.
It's worth noticing that despite all the FUD on the internet, it is pretty clear that when the science is done, hybrids are better than fossil-fueled internal-combustion engines.
But that doesn't make hybrids a sustainable option. If you're putting fossil-fuel in, they're not.
There are other, more sustainable options, and these will depend on your real trip patterns. For many households, an electric-vehicle for the vast majority of daily travel that's less than 120km, and borrowing / hiring / sharing a different vehicle for the occasional longer trip, will do.
The trade-off will depend a lot on your particular circumstances: if you've got an older biodiesel vehicle, it will depend on the lifecycle emissions of your biodiesel supply, and that will vary hugely around the world. If you get a hybrid, will it be biodiesel / electric hybrid, or something else? If biodiesel-electric, then it will almost certainly be better than an older biodiesel vehicle. If fossil-fuel electric, it could be worse, if your current biodiesel supply is pretty clean. Note that in that latter case, there will be trade-offs between local and global pollutants.
I have driven a hybrid since 2000 and noted that I get 39.6 miles per gallon. This is primarily due to the fact that I do mostly freeway driving. I do get much better gas mileage when using city streets. This is because at lower speeds the hybrids will use the battery for power in place of gas. So when looking at a car you may want to take into account your driving habits.
It's a question of your driving habits. How many miles do you put down. Ddesels are notoriously reliable and biodiesel is less polluting to air than normal petro diesel, never the less factor in what rough conditions or miles you put on a used car, if after 50,000 miles you're car finally goes up? On average a hybrid car uses 25-50% more energy to manufacture than a normal gas car, so amortization accumulates only after the accumulated years of driving. In short changing the fuel type is meaningless, Biofuels are notoriously questionable for the environmental. deforestation in the tropics to meet demand for oils (Palm, etc) to make biodiesel. Biodiesel derived from used cooking oil, more suitable but requires refinement. The real solution is simply driving less regardless of vehicle choice.
It's an old subject but there is new information with new car configurations coming out.
To start with, I do like turbo-diesels if they also have urea-injection in the exhaust. But most car makers gave up on urea-injection and instead cheated on the emission tests.
For hybrids, I recommend using the hybrid system only to assist the primary engine and in that way the hybrid system will last more of the day. Using the hybrid system for an all-electric mode just quickly wipes-out the system. (In fact MB has a hybrid 3.0 inline-six engine such that an extra-large starter motor just begins moving the car from a stop, at which point the engine picks-up with an electric supercharger, and that gives the single turbocharger time to develop boost such that the turbocharger then takes-over from the supercharger. Of course the turbocharger is run by the exhaust while the supercharger is run by the electrical system.)
But most often I would avoid the weight, complexity, and cost of a hybrid car and get something else instead. And so there are now premium rear-wheel-drive coupes and sedans with 2.0 turbocharged engines and no hybrid system. These cars are available from BMW, Cadillac, Chevrolet Camaro, Genesis, Jaguar, Kia, Lexus, and Mercedes Benz. In fact, BMW, Jaguar, and MB also have rear-wheel-drive roadsters with 2.0 turbocharged engines.
Now the 2.0 turbocharged engine reduces vehicle weight compared to a V6 engine but make almost as much power as a V6. Furthermore, the 2.0 turbocharged engines have a large amount of low-end torque and are easy to drive.
Two rear-wheel-drive cars with 2.0 engines that are not turbocharged are the Mazda MX-5 roadster and the Toyota 86 coupe.
The notable battery-powered electric-vehicle is the BMW i3 which has a carbon-fiber bodywork such that the car weighs less than 3000 pounds.
Overall, consider the new model cars that are coming-out but that have actually been available for a few years now.
The important thing to realize here is that biodiesel is not sustainable in the required quantities.
Sure, you can produce biodiesel from waste, but only a little bit. How does it help that 1% of transportation fuels are created from waste? Not much.
You can also produce biodiesel from oil palms. For example, if you cut down all rainforests in this planet to create oil palm plantations, the produced palm oil could fuel our carbon-based society by renewable fuels. But I don't consider this a desirable scenario. The biodiesel producing companies are claiming their biodiesel is sustainable because it's sourced from certified oil palm plantations that aren't situated in cut-down rainforests. However, if the usage of these "green" biodiesel fuels increases, then some less affluent people will see that the price of sustainable palm oil goes so high that they have to buy non-sustainable palm oil produced in plantations situated in cut-down rainforests. So the increase in palm oil use led to more unsustainable plantations even though the biodiesel consumer believes his biodiesel is "green".
If you install carbon dioxide capture equipment to all pulp and paper factories worldwide and use green electricity (wind, solar) to create hydrogen by electrolysis and combine the hydrogen with carbon dioxide to firstly methane and then later post-process it to liquid fuels, the produced fuel amount won't be great enough to offset all oil uses currently supplied by fossil petroleum. (And besides, the fuel would be so expensive nobody would buy it.)
So, a large change in the energy system needs to happen. Energy needs to be in a form that doesn't emit carbon. 1 liter of biodiesel emits just as much carbon as 1 liter of fossil diesel, because we can't produce enough sustainable biodiesel. It doesn't matter that a small percentage of fuel usage could come from sustainable sources -- if all won't come from sustainable sources, then we need to reduce the usage of carbon based fuels.
A new hybrid vehicle is probably more fuel efficient than an old diesel vehicle regardless of whether it burns biodiesel or fossil diesel. Thus, it emits less carbon per mile than a diesel vehicle. That's what counts.
You need to realize that "green" fuels are a finite resource. If the world can produce a given amount of liters of "green" fuels, and if somebody decides to buy those "green" fuels, it means the increased demand for these "green" fuels causes the producers to increase prices because they can't increase production past the supply limit. This increase of prices mean somebody else previously consuming these "green" fuels decides they are too expensive and switches to dirty fossil based fuels. A decision to buy "green" fuels thus didn't result in any benefit for the environment.
