1. To spark the fuel
   To warm up the cylinders
2. To make the whole engine hot
   To help you see what you're doing

Too many people think glowplugs work like spark plugs in gasoline-powered engines, but they're not similar at all. Glowplugs heat up the air in the engine's cylinders, making the combustion process easier when you're trying to start up the engine in especially cold weather.

1. Duramax 6.0-liter V-8
   Cummins 3.6-liter V-6
2. Duramax 2.8-liter
   Triton 6.4-liter V-8

You might be surprised that the pickup truck uses such a small diesel engine, but it boasts impressive performance. Sure, the max 181 horsepower isn't anything to scream about, but the 369 lb.-ft. of torque puts the Colorado well above competitors where it really counts.

1. 3.6-liter Duramax
   2.0-liter TDI
2. 3.0-liter TDI
   4.6-liter Cummins

While it wasn't the only engine involved in the Dieselgate emissions cheat scandal, the 2.0-liter TDI was the main focus, thanks to the sheer number of them on roads around the world. Ultimately, the scandal cost the Volkswagen Group billions in fines and restitution.

1. 32 degrees
   28 degrees
2. 20 degrees
   10-15 degrees

Diesel fuel normally flows without any problems, but when it gets this cold, it gels and starts to clog the tank and fuel filters. As you can probably imagine, that makes starting a diesel engine in super cold temperatures difficult, unless you can safely apply some heat.

1. They're weaker
   Higher compression ratios
2. They break easily
   Poor design qualities

Because diesel engines ignite the air/fuel mixture through extreme compression, everything inside the engine, from the connecting rods to the pistons and crankshafts, must be thicker and stronger. That means they're thicker, so it takes more energy to spin them quickly, making it more economical to run the engines at lower RPMs.

1. It's atomized
   It's sprayed upward
2. It's sprayed downward
   Nothing

Atomizing diesel fuel involves breaking it into small droplets, or a fine mist, really. The whole point is so the fuel mixes better with the air in the combustion chamber, which increases efficiency since more of the fuel burns up.

1. It sounds cool
   Because diesel needs exhaust fumes
2. It boosts efficiency
   They run at higher RPMs

Because diesel engines typically run at low RPMs, it's difficult for them to draw enough air into the cylinders. That's where the turbo system comes in, since it crams more air through, smoothing out performance and boosting fuel efficiency.

1. They produce lots of torque
   They produce a lot of horsepower
2. They sound better
   It's a tradition thing

Not only do diesel engines tend to make way more torque, which is key to pulling big loads or towing heavy trailers, they're in general more durable than gasoline engines, making them perfect for working vehicles that rack up a lot of miles and put up with tons of abuse.

1. Curt Von Oilburner
   Dietrech Ulchdorf
2. Henry Ford
   Rudolf Diesel

In the late 1800s, Rudolf Diesel was in the Polytechnic High School of Germany when he learned about how inefficient gasoline and steam engines were. He set out to create a more efficient engine, which, of course, was the diesel.

1. Racing
   Spec
2. Crate
   Boat

This crate engine appeals to plenty of enthusiasts who want to put a diesel in their ride. It comes with plenty of peripherals, including the remote oil filter, power steering pump, alternator, and throttle pedal.

1. 3.6 liters
   2.7 liters
2. 2.0 liters
   1.6 liters

The turbocharged DOHC inline four-cylinder engine features an aluminum block and cylinder head, plus direct fuel injection. The setup is good for a peak 137 horsepower, plus 240 lb.-ft. of torque, which is pretty impressive for a compact sedan.

1. The valves
   The pistons to the crankshaft
2. The two camshafts
   The driver to the road

Just like in gasoline engines, diesels have connecting rods that transfer the downward movement of the pistons to the crankshaft, which transforms that energy into a spinning motion.

1. Coolant
   Water
2. Oil
   Fuel

Just like with gasoline engines, most modern diesels have a water jacket incorporated into the block, which is passageways for the coolant to flow through. It's true that clean oil can help remove some heat from the engine, but the primary function of oil is to lubricate engine components.

1. The cylinder walls
   The glow plugs
2. The air
   The oil

As the air and fuel mixture in the cylinder is compressed, it gets to the point that the air molecules rub against each other so much, they heat up. That in turn ignites the fuel, which is what makes a diesel engine work.

1. 4
   3
2. 2
   1

Diesels have the following four strokes for the combustion cycle: intake, compression, combustion, and exhaust. These, of course, happen at different times in the various cylinders, depending on the engine design.

1. Through the intake valve
   Direct injection
2. Through the fuel rail
   Through the turbo system

Before direct injection became the thing in gasoline engines, diesels already used this design, which is more efficient. That means the fuel doesn't mix with the air until it's sprayed into the combustion chamber.

1. 7.2-liter Cummins
   5.6-liter Power Stroke V-8
2. 4.8-liter Cummins
   3.0-liter Power Stroke V-6

For the first time in the history of the F-150, you can get the truck with a diesel engine. With 250 horsepower and 440 lb.-ft. of torque, It can handle up to 11,400 pounds for towing, which is pretty impressive.

1. Spark plugs
   High pressure fuel injection
2. An igniter
   Cylinder wall friction

When you turn the key in the ignition, you're not triggering any kind of spark. Instead, fuel sprays into the cylinders under so much pressure that it heats up the air, triggering combustion. This can take a second or two, depending on how cold it is outside.

1. Refined diesel
   Peanut oil
2. Bacon grease
   Hot dog water

Biodiesel, or diesel that's made out of agricultural materials, has often been seen as a fringe movement. It's funny to consider that was the roots of the diesel engine movement, since Rudolf Diesel used a readily available fuel for his design.

1. Cummins 5.0-liter V-8
   Cummins 9.0-liter V-8
2. Cummins 7.3-liter V-8
   Cummins 6.2-liter V-8

Nissan really turned a corner in the truck market when it teamed up with legendary diesel engine brand Cummins. This setup in the Titan XD is good for a max 555 lb.-ft. of torque, making the truck appealing to people who need extreme towing or hauling power.

1. They go through oil constantly
   Diesel fuel is a type of oil
2. Oil is burned in the exhaust system
   They really run on engine oil, not diesel

Technically speaking, diesel fuel is a type of oil, while biodiesel is not. The term "oil burner" is an old one, but it has stuck around for decades, although pretty much only enthusiasts refer to diesels this way.

1. Every 5,000 miles
   Whatever the manufacturer recommends
2. Every 20,000 miles
   Every 50,000 miles

Just like with gasoline-powered engines, diesels require fresh oil to run properly, otherwise you're going to get some metal-on-metal action that could ruin the entire engine. Just how often you should change the oil is recommended in the owner's manual, or you can contact your local dealer's service department for that info.

1. GreenWave
   GreenCrystal
2. BlueTEC
   OilBurning

Mercedes-Benz has a long history working with diesel, although it landed a really bad reputation in North America ​in the 1980s for diesels that would belch black clouds out the tailpipe. The BlueTEC name is supposed to help transform that image, emphasizing that the new technology doesn't produce excessive emissions.

1. Two
   One
2. Four
   Three

To keep the fuel injectors free of any clogs, you must change out these filters periodically. Some are changed out similar to an oil filter, while others contain a cartridge for an even easier time. You should change the filters per the manufacturer's recommended intervals.

1. Diesel fuel isn't as harsh
   They're made more rugged
2. They don't corrode
   Diesel is magical

Because diesel engines must endure greater forces, thanks to higher compression necessary for combustion, they're overbuilt compared to gasoline engines. Those sturdier parts last longer, hence the longevity of diesels.

1. Cobalt
   Zinc
2. Water
   Copper

Because diesel has a tendency to absorb water more than gasoline does, most diesel engines have a water separator. As you probably can guess, this device collects water from the fuel, so that water doesn't enter the combustion chambers, where corrosion issues might become a problem.

1. Valve
   Gasket
2. Glow plug
   Exhaust Separator

Just like in a gasoline engine, diesels use valves to control the flow of air into the combustion chamber, as well as the release of the exhaust gases after combustion.

1. Tempering with the emissions system
   Shoving crush coal into the fuel tank
2. Driving any diesel truck
   Doing a burnout

Rolling coal is a controversial practice typically popular among certain diesel pickup truck owners. They modify the emissions system so the truck will spew dark clouds of soot out of the tailpipe, mostly to annoy other drivers and look "cool."

1. Regular diesel
   Water
2. Orange juice
   Worms

While you could put pure biodiesel in your car or truck, you typically get the best overall performance by mixing it with regular diesel fuel. If you buy biodiesel, the rating like B20 or B60 indicates what percent is biodiesel.

1. Through the clutch
   Through the wheels
2. Osmosis
   Heat transference

Just like with other vehicle engines, the spinning motion from the crankshaft is transferred to the clutch via the flywheel. The clutch acts as that interface between the engine and transmission, which are almost always moving at different speeds.

1. BCT
   TDI
2. DieselPower
   DieselInjens

TDI stands for turbocharged direct injection, because all modern Volkswagen diesels share that setup. Of course, Volkswagen has shifted from diesels and is moving toward electric cars, thanks to the Dieselgate scandal and its fallout.

1. GMC Terrain
   Saturn Vue
2. Buick Encore
   Jeep Rebel

Not only can you get the GMC Terrain with a diesel, the Chevy Equinox can be had with the same 1.6-liter turbocharged four-cylinder diesel engine. Like other diesels, it promises amazing fuel economy.

1. 2.3-liter Cummins
   3.0-liter EcoDiesel
2. 3.5-liter Cummins
   4.6-liter turbo diesel

You might already know the 3.0-liter EcoDiesel from the Ram lineup. Not only will it provide great efficiency, the EcoDiesel produces plenty of torque, which is great for off-roading through particularly difficult terrain, like mud.

1. Twin barrel
   DOC
2. Oxygenated
   Copper

Diesel oxidation catalyst (DOC) catalytic converters feature aluminum oxide, platinum, and palladium as the catalysts. They help oxidize hydrocarbons and carbon monoxide by combining with oxygen, creating carbon dioxide and water instead.

1. 500D
   523D
2. 540Di
   560D

Many have proclaimed that the BMW 523D is the quietest diesel engine they've ever experienced. Reviewers have also remarked that it's surprisingly refined, not creating any vibrations in the car, and delivering smooth power throughout the RPM range.