1. No
   Sometimes
2. Only expensive ones
   Yes

Spark plugs do come gapped already, but that doesn't mean they're in line with your engine's specs. Manufacturers make spark plugs that are the same configuration, but work on a whole range of engines, so it's impossible to have them all gapped to suit each engine, which is why you must check them yourself.

1. it's running extra lean.
   It makes a lot of power.
2. It's running extra rich.
   Turbochargers make flames.

Unless someone has installed a cheesy aftermarket flame kit for their exhaust, this is caused by the car running extra rich. The extra fuel that makes its way into the exhaust system burns up there, so flames shoot out the exhaust tip. Technically, you could do this with any vehicle.

1. 4/32 inch
   3 inches
2. 1 inch
   2/32 inch

Some people like to use a penny to check for this depth, because when you can see all of Lincoln's head, it's time to get new tires. Of course, you could just use a tire tread depth gauge, which costs surprisingly little.

1. Loss of braking power
   Braking lightly on a downhill
2. When your brake pads get too low
   When the brake fluid drops below the minimum level

The most common cause of brake fade is when you ride the brakes, which generates so much heat the brake fluid boils and no longer applies the necessary pressure. Excessive friction alone, as well as mechanical problems, can also be the source of this dangerous issue.

1. Hand tight
   As tight as you can stomping on the tire iron
2. To 18 lb.-ft. of torque
   Torqued to spec

Every automaker will give you the lug nut torque specifications, which you really should follow when putting the wheels back on. If the lug nuts are too loose, you risk the wheels wobbling or coming off. If they're too tight, you can damage the wheel, bolts or the hub.

1. Battery going out
   Bad alternator
2. Low battery juice
   Bad bulbs

As you're driving, the power to run things like the radio, lights, etc. comes from the alternator, which also recharges the battery. The battery primarily provides enough spark to start the engine, which can be an issue if you have a bad alternator. Fortunately, it's relatively easy to have yours tested.

1. Screeches
   Catches mice
2. Muffles noise
   Reduces emissions

Modern cars have catalytic converters as part of the exhaust system. The convert harmful gases in from the engine into less harmful or completely harmless gases, so less pollution goes into the air.

1. Long and wide
   Short and wide
2. Long and focused
   Short and focused

Because fog lights are mounted low and scatter light broadly, they can help with seeing in bad visibility conditions, because they don't reflect light back into the driver's face. However, driving with them on in regular conditions can be annoying for other drivers, so keep that in mind.

1. Every 6 months
   Every 6,000 miles
2. Once a year
   Whenever the manufacturer says to do it

Thanks to different engine designs, plus modern innovations in oil technology, some cars can go a long time between oil changes. The best thing to do is consult your owner's manual to ensure you're taking proper care of your vehicle, without spending too much on oil.

1. With a box fan
   In a wind tunnel
2. Driving in the wind
   By caking the car with flour and then driving

In modern times, automakers will use computer simulations to design exterior parts for a concept or prototype vehicle, which virtually measures aerodynamic drag. Still, they also put vehicles in a wind tunnel to get actual measurements, and make adjustments as they're necessary to ensure optimal efficiency and performance.

1. It crams more exhaust into the engine.
   it cools intake air.
2. It increases the combustion chamber size.
   It cuts down on curb weight.

Back in World War II, the U.S. Air Force fogged nitrous oxide into the bombers' engines to help with quick air raids. The GIs brought this trick back home with them, and started doing the same thing with their cars. Because this chemical compound cools the air, you get more oxygen molecules in the cylinder, which leads to a more powerful burn, increasing power.

1. Toothpaste
   Store-bought kits
2. Glass cleaner
   Insect repellent

Over time, the plastic headlight lenses cloud as they oxidize from sitting in UV light from the sun. All the methods people use to clear up this issue essentially strips a layer or more off the headlight lenses, removing the oxidization with it, so everything is clear again.

1. Blocked oil filter
   Overheating engine
2. Blown head gasket
   Low octane fuel

Usually, milky oil comes from coolant mixing with it, which usually happens when the head gasket on your engine blows. It's possible for the two to mix otherwise, but not likely. Also, milky oil could be from moisture collecting in the combustion chambers.

1. Right behind the wheels
   Under the transmission and engine
2. On the jack points
   It doesn't matter.

The jack points for different vehicles vary, but usually they're behind the front wheels and in front of the rear wheels. Just look at the owner's manual to see where the manufacturer recommends placing them, and to see where you should jack up the car.

1. Until they look full
   Match the number printed on the sidewalls
2. Follow the door jamb sticker
   30 psi for cars, and 40 psi for trucks/SUVs

You should always look at the sticker placed in the driver's door jamb, the owner's manual, or call the dealership to see just how much air to put in your car's tires. It really does depend on the exact model, so never just guess or use any other information.

1. To keep your keys from flying out of the car
   To protect your head in a crash
2. To guard your upper torso
   To keep glass from flying into the car

While side curtain airbags certainly were made primarily to protect everyone's head, they also help keep your arms from flailing out the window, which could cause a serious injury, including your arm becoming trapped up the car if it rolls.

1. Behind the glove box
   Under the floor boards
2. Right next to the firewall
   Next to the AC compressor

You might think swapping out this air filter is difficult, but it's actually a cinch. Most modern cars have a simple way to unhook the glove box or flip it down far enough that you can reach the filter easily, making it a job anyone could do.

1. Negative cable on the dead car
   Negative cable on the working car
2. Positive cable on the dead car
   Positive cable on the working car

Not grounding on the car that isn't working can have serious consequences, so just do it. Also, the working car should be tuned off as you make the connections, just so there isn't any risk of getting shocked or worse. And put the parking brake on both cars, just in case.

1. The tread will wear out
   Mice will live in them
2. Water will collect there
   They'll develop flat spots

This risk is real if you're storing a car for the long term. If you have tires that are mounted to wheels or not, investing in a simple rack that gets them up off the ground is worth it. Once tires have flat spots, you likely need to buy replacements, and that gets expensive.

1. Never changing the oil
   Driving through a four-foot-deep pond
2. Having it serviced at an independent shop
   Replacing the camshafts with performance versions

Some dealerships will try to convince you that your car must be serviced there for the warranty to not be voided. If you have a reputable shop do the manufacturer-recommended maintenance, you shouldn't have a problem.

1. It moves energy from the engine to the transmission.
   It converts gas to the right octane.
2. It allows the wheels on an axle to spin at different speeds.
   It helps you accurately gauge your speed.

Without a differential, your car would have a problem with turns. It allows the inside wheel to spin less than the outside as you go through a turn. Rear-wheel-drive cars usually have the differential in a separate housing, where it uses its own lubrication system.

1. The battery
   The coolant
2. Gas fumes
   The sun

As the coolant flows out of your car's engine, it goes to a compartment called the heater core. There, heat from the coolant can be blown by a fan into the cabin. That means the coolant is what really powers your car's heater, which is why being low on coolant can suddenly turn the heater cold.

1. Tires
   Exhaust
2. Oil
   Plastic

Turbochargers literally run off the exhaust gases from your car, essentially recycling them. This gives your engine an instant boost as more air is crammed into the cylinders, especially considering most modern turbos use an intercooler to avoid pushing hot exhaust gases back into the combustion chambers.

1. Less than 1/4 inch
   Less than 1/2 inch
2. Less than 3/4 inch
   Less than 1 inch

Not only does a puncture need to be small for it to be repairable, it can't be on the shoulder or sidewall, otherwise you'll have to just replace the tire.

1. Fuel
   Air
2. Oil
   Water

Direct injection means the fuel injectors spray right into the combustion chamber. Some engines are set up for this to happen right before the spark plugs ignite the air-fuel mixture, which can make everything run more efficiently.

1. Puts the transmission is a higher gear
   Turbocharges everything
2. Starts you in second gear
   Makes the transmission work harder

So many people talk about kicking things into overdrive, which means working harder and pushing everything to the limit. In cars, overdrive actually helps the transmission work less by using a higher gear, which in turn saves on gas.

1. The glow plugs
   High compression
2. Spark plugs
   Nobody knows

Unlike gasoline engines, diesel engines don't have spark plugs to ignite the fuel. Instead, they place the air-fuel mixture under so much pressure, the fuel combusts, which is partly what makes them so efficient.

1. The possibility of the pistons slapping each other
   When the camshaft touches the valves versus not touching them
2. The possibility of the valves and pistons contacting each other
   Whether or not your engine interferes with weekend plans

If you have an interference engine, when the timing belt or chain breaks, you might be facing some serious internal damage, requiring a rebuild. Of course, non-interference engines don't present this challenge.

1. The check engine light turning on
   The car exploding
2. Rough idle
   The fuel pump burning out

Depending on your car, you need to turn the gas cap until it clicks once or three times. It's also a good idea to give a little tug on the cap, ensuring it's seated all the way, before you turn on the engine and start driving.

1. Excessive wear in the center of the tread
   Excessive wear at the edges of the tread
2. Quick acceleration
   Better fuel economy

There are a lot of drawbacks to not inflating your car's tires enough, including bad fuel efficiency, decreased acceleration, and poor cornering performance. You should check the inflation regularly, like once every month or so, to prevent these problems.

1. Eliminates surface scratches
   Protects against rust
2. Gets rid of swirls
   Cleans up dirt

Really, you should be waxing and polishing your car's paint regularly, not just one or the other. Both are key to having a car that looks excellent for some time, instead of dealing with paint that has a poor appearance.

1. Rough idle
   The engine blowing up
2. A blown head gasket
   Backfiring

When the boot on an ignition wire, which is supposed to sit firmly on the lip around a spark plug well, slips off, your engine loses some compression. That means it runs rougher than before, which hurts performance as well as makes for a less comfortable ride. Fortunately, this problem is super easy to correct.

1. Seal up automatically
   Help you see better
2. Become huge instantly
   Knock a hole in the roof

All it takes is a little bit of moisture getting into the crack, and as it freezes that water expands quickly. The result is a small crack becoming a big one in about one second, sometimes so violently it will scare you as the driver.

1. The throttle
   The gas flow
2. The wheels
   Your mom

Whether electronically or mechanically, the accelerator pedal in your car determines how wide the throttle opens. The onboard computer then adjusts the flow of fuel accordingly.

1. The battery is dead
   The alternator is going out
2. Blown fuse
   The horn is blown

Something as little and simple as a fuse can cause all kinds of electrical problems on your car. The horn is electrical, so you should always check the fuse first before deciding the horn itself needs servicing.