Basic Driving and Safety: Crash Physics, Belts, Child Seats, Air Bags, Vehicle Checks, Steering, Cornering and the Seasons: the Three Collisions and Newton's Laws, Belts for Everyone Front and Back, the 50 Percent Rule, Child Seats From Rear-Facing to Age 13, the 10 and 2 Danger and 10 Inches From the Wheel, Active and Passive Safety, Weekly and Monthly Checks, Adjusting the Seat, Starting, Stopping and the Steering Lock, Physical, Social and Mental Skills, Fuel-Saving Habits, Tire Types, Oversteer and Understeer, the Four Steering Methods and 180 Degrees, the 10-Point Cornering Plan, and Spring, Summer, Fall and Winter Driving

Written for aiforu2 as the source for a practice-test bank and the on-device tutor for the Louisiana Class E knowledge test. The facts follow the official manual; the wording is ours.

Source: Louisiana Class D & E Driver's Guide (OMV, R08/25 edition), Chapter 4 "Basic Driving and Safety" (pages 38–53).

The anatomy of a crash

Crashes injure because force exceeds what people and property can absorb; properly restrained occupants withstand a great deal, and higher speed means worse injury. In a crash your car hits something and is badly damaged even at 30 mph; then you hit the car, thrown into the windshield, dashboard or wheel if unbelted; then your organs hit your bones as the brain strikes the skull and the lungs the ribs, causing internal injuries. Newton's laws govern: a body in motion stays in motion unless acted on; stopping needs force, and momentum is mass times velocity, so a bowling ball takes far more force to stop than a marble; and in a collision each car feels equal and opposite force, but the lighter car changes velocity more and suffers more. The best protection is buckling up every time, obeying the speed limit and driving safely.

Safety belts

Louisiana's mandatory belt law covers all passengers, front and back, in cars, vans and pickups. The three-point belt saves more lives than any other device, cutting serious injury and death by 50 percent, and belted occupants are three to four times likelier to survive; still, teens, commercial drivers, rural men, pickup drivers, night drivers and drinkers are least likely to buckle up. Wear the lap belt snug across the hips, whose bones absorb impact better than the abdomen, and the shoulder strap over the shoulder and across the chest. Belts keep you from being ejected (almost always deadly), keep rear passengers from being thrown into others, reduce the chance of being knocked unconscious, let you escape fire or water, and keep you behind the wheel in control. A pregnant woman and her unborn child are safer belted. Belts cut serious injury and death by 60 to 80 percent and are your best defense against a drunk driver. Eighty percent of deaths happen under 40 mph, 75 percent of crashes within 25 miles of home, being thrown out makes death 25 times likelier, unbelted deaths have occurred at 12 mph, each of us can expect a crash about once every ten years, and the chance of being trapped in a burning or submerged car is under half of one percent. One adult in seven still refuses to buckle up.

Child restraints and air bags

Under the child passenger restraint law every child must ride in an age- or size-appropriate federally approved system: birth to at least 2 rear-facing; 2 to 4 forward-facing; 4 to 9 a booster with restraints; 9 and up a properly fitted lap-shoulder belt; and children under 13 in the rear seat when available. A child who fits two categories uses the more protective one. Never hold a child on your lap, share one belt with a child or let a child stand on a seat; the middle of the back seat is safest. An air bag inflates in a frontal or near-frontal crash, supplements belts and does not replace them; because it deploys at 150 to 200 mph, the old 10 and 2 hand position can throw your hands into your head, break a wrist or sever a thumb, so hold the wheel at 9 and 3 or 8 and 4. Pickups and sports cars with small or no rear seats have a passenger air bag on-off switch for carrying a child 12 or under in front. Sit at least 10 inches from the wheel, tilt it toward the chest, and seat older frail people and children 12 and under in back; air bags do not deploy in a rear-end crash. Headrests prevent whiplash, steering wheels now absorb impact, dashboards are padded and front ends crumple. Active safety technology prevents crashes (lights, mirrors, brakes, steering, and driver assistance such as automatic braking, night vision, adaptive headlamps, backup sensors and cameras, blind spot warning, adaptive cruise, lane departure warning, tire pressure monitoring, traction control, stability control, ABS, brake force distribution, brake assist and parking systems); passive safety protects during a crash (belts that stretch to slow deceleration, air bags, laminated windshields that stay in one piece, tempered side glass that granulates, crumple zones, side beams, collapsible steering columns, padding and cargo barriers). Lighter-colored cars appear in fewer crashes.

Vehicle condition and preparing to drive

Fix defects promptly; if coolant, oil, battery water, tire pressure and lamps have not been checked in a week, check them. Dispose of oil and batteries properly and donate rather than abandon an old car. Weekly, check tire pressure against the range on the tire, tread of at least 1/16 inch, even wear and no dry rot, bulges or separation, oil level, battery corrosion, leaks, radiator level, unbroken and working lights, the horn, the fuel cap and belt wear; monthly, check mirrors and windows for cracks, the plate's readability, brake lights and flashers, wiper blades, the spare, jack and emergency gear, and power steering, brake, transmission, oil and battery fluids, with the engine cool and the parking brake set. Before entering, check tires, leaks, clean lights and mirrors, walk around for obstacles and children, and never drive impaired. Inside, clean the windows, adjust the seat and head restraint and mirrors, close and lock the doors, be in park or neutral, belt everyone, check the gauges, wipers and washer fluid, and be mentally and physically ready. Adjust the seat so the headrest fully supports your head, your elbows stay slightly bent on the wheel (leaving air bag room, at least 10 inches away), and your knees bend slightly with the right heel planted so the foot pivots between gas and brake. Turn the key smoothly, accelerate gently with the ball of your foot and toes, hold a steady speed, check the speedometer, brake smoothly, and stop far enough back to see the bottom of the tires of the vehicle ahead. Look for pedestrians and traffic before moving, turn your head when backing, and never turn the ignition to lock while moving, which locks the steering. Driving takes physical, social and mental skill.

Habits, fuel and tires

Repetition breeds bad habits; safe defensive driving is a skill. Poor efficiency comes from strategic (tuning, tire pressure, oil), tactical (route, congestion, load) and operational (idling, speed, aggression, cruise control, air conditioning) choices; route, speed and tuning matter most, and a 30-mpg car driven badly can fall to 17 mpg. Vehicle occupancy has fallen, so more cars carry only the driver. Save fuel by tuning the engine, inflating tires (worth up to 3.3 percent in mileage), using the right oil, logging fill-ups, obeying the limit, shedding weight, avoiding peak traffic, using cruise control on highways, avoiding stop-and-go and idling, combining errands and parking in shade. The correct pressure is on the driver's door jamb sticker. All-season tires suit wet and dry but not ice; performance tires suit dry weather only; winter tires handle snow and ice but are damaged by dry roads.

Steering and cornering

A well-designed car warns before skidding as tires slip sideways (the slip angle). Oversteer, when the rear tires lose grip first and the rear slides outward so the car turns more than intended, is likelier in rear-wheel-drive cars and can spin the car; slamming the brakes makes it worse, so gently reduce the steering angle and ease off the gas. Understeer, when the front tires lose grip first and the car turns less than intended, is safer, likelier in front-wheel-drive cars, and worsened by adding steering; lift off the gas and brake to shift weight onto the front tires. Four steering methods: hand-to-hand (push/pull) for normal driving above 10 to 15 mph, hands at 7-to-8 and 4-to-5, working between 11 and 8 with the left hand and 1 and 8 with the right, never crossing the wheel (10 and 2 is not recommended with air bags); hand-over-hand at low speeds such as intersections and parking, hands at 8-to-9 and 3-to-4 using the top third of the wheel; evasive action steering with ABS engaged, limiting input, since modern cars need only 45 to 90 degrees to return to the road and more than 180 degrees loses traction and sends the car across the road; and one-hand steering only when backing or reaching for a control, keeping the other hand at 8-9 or 3-4, with 12 o'clock recommended only when backing while turned in the seat. Every corner has an entry, apex and exit; the 10-point plan: both hands at 9 and 3; look as far around the bend as possible, since the eyes steer the car; use judgment and safety margins; remember cornering force rises with speed squared, so doubling speed quadruples it; slow in; smooth is safe; ease off the gas at entry to load the front wheels and keep out wide without crossing the center line on a right turn; add a little gas mid-corner, easing off and adding steering if you run wide; accelerate gently and unwind the wheel at the exit; and plan the corner before you reach it.

Seasonal driving

Spring brings rain that mixes with oil into slick film, so slow down and add following distance even in mist; more motorcyclists, bicyclists and pedestrians; allergy medicines that impair; potholes that knock out alignment; puddles that impair brakes and cause hydroplaning; and the need for proper inflation. Summer: check the air conditioning and never leave pets or children in a car; service the car; check all fluids; carry current maps and share your itinerary; do not exceed payload capacity; remember pressure rises about one pound per 10 degrees Fahrenheit; obey construction zones; shade the windshield; and relearn school zones. Fall: wet leaves are slippery and dry leaf piles can be ignited by a catalytic converter; the end of daylight saving time cuts visibility; temperature swings drop tire pressure; sun glare calls for sunglasses and anti-reflective lenses; and rain brings hydroplaning, in which you steer straight and gently release the gas until the tires grip. Winter: headlights make you visible in rain, snow and fog; avoid driving in bad weather; winterize brakes, wipers, defroster, lights and heater; stop gently and ease off if the wheels lock; turn on and clean the lights; slow down and lengthen the gap; look ahead; clear the hood, windows and roof; use snow or all-season tires or chains, since no tire allows normal speed on snow; expect bridges, overpasses and shade to freeze first and stay icy; never drive faster than the wipers can clear; and carry emergency supplies and stay with the vehicle if stranded. The most important safety feature of any automobile is the driver.

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