An aspect often overlooked is the driver's seating position. Rally drivers can spend even more than six hours on ajdusting the seat in a new car, driving along and experimenting different variations of the seating position. A good seating position has three objectives to achieve:
Seating positions in normal road driving and race driving are not to be distinguished. The idea in both is to sit quite upright and vertical, relatively close to the steering wheel and pedals.
Adjusting the driving posture
Configuring a proper posture is perhaps the most important action you do before driving the car. The idea is to allow the seat to provide maximum support to the back, scapulae and thighs, as well as to prevent any outstretching of the limbs forward. The posture should also yield good side support against the forces working on the driver (accelerating during braking and lateral acceleration in corners), a good forward visual field and a safe position in a collision.
With the exception of fire-proof racing gear, comfortable clothing that does not limit the driver's motions is a must. This includes pants that go at least as low as the knees and shirts with sleeves up the elbow. It's important to use good shoes, such that will protect the foot, provide good dampening for pedal feel and allow to fully depress the pedals. A good shoe is snug-fitted, thin-soled with a slightly dense sole and a flat heel.
Sitting and the seat
The driver should push his pelvic and lower back deep into the corner of the seat, and provide full contact with the backrest and the back. Modern car seats are build with ergonomics and side support in mind, and will category diminish all back problems if the sitting is proper and the posture is adjusted properly. For racing purpose, a racing seat can be good, if it is used in conjugation with a proper harness and with some roll protection. Nevertheless, the stock seats and seatbelts in modern cars are quite effective by themselves.
The Seating Distance
The distance of the seat relative to the pedals and steering is the first aspect to be adjusted. Our goal is to adjust it forward to a position where under full pressure to all pedals, the knees remain bent. If the knee flattens out and becomes bolt-straight the positioning is too far to the back. The foot will be unable of applying pressure to the pedal effectively (due to the lost of the torque exerted by the quadriceps and across the knee) and, should a collision be due, the driver - in his attempt to brake and to push himself away, will lock the joint. In this situation, the shock omitted through the pedals will break the knee rather than bend it. The hit that will push the pedals back, will not be absorbed into outstretched muscles will be transmitted directly to the bones, causing fractures all across the leg, even up to the pelvic or even the base of the spine.
Being too close isn't good either, since the knee is likely to be positioned in a way that will lift the thighs from the seat, reducing body support. The transition from pedal to pedal would feel awkward and the blood circulation through the leg will not be as effective. Also, in a collision, the knees are likely to hit the under-dash. We are looking for a knee that reaches a maximum angle of 140 degrees, or 120 for racing purposes. To ensure the check is accurate, make sure you depress the pedals with the engine turned on. The brake pedal should be pressed a few times before the actual check, as to build up pressure in the booster.
The Rake of the Back
Bring the backrest to a relatively upright angle. This is supposed to allow us to be close enough to the wheel with our upper body so we can operate it fully with our arms, but without unnecessary back motions. Moving the back forward would mean that the steering is too far away, and this will mean that we loose the support of the seat and can be thrown about inside the car with nothing but the steering wheel to brace ourselves against, which will make us turn the wheel in unwanted directions. The steering column is angled down to reach the steering rack that connects to the front wheels, so it is tilted in an angle away from you. Our goal is to bring our back to be as parallel as possible to the steering.
However, there is such a thing as too upright. If the seat is perfectly erect at 90 degrees -- it will put too much stress on the lower back and will reduce the side support efficiency of the seat. We need to bring it to a relatively upright angle and than play with the other adjustments like the steering wheel adjustments and the seat height, to reach a good outcome.
The adjustments of the steering wheel
Modern cars allow to adjust the steering height in an arch, and often to adjust it inside and out. The cars that have the latter option usually allow for a near-perfect posture, especially for those with long arms and short legs, or vice versa. The adjustments are supposed to allow a good reach of the wheel, as well as a comfortable grip of it and a clear view at the instrument cluster. The higher the steering wheel is, the higher are our arms holding it relative to our shoulders. This makes us lean our arms forward so the grip becomes more of a toll to the shoulders, but allows to steer more freely.
The lower the steering wheel is, the easier it is to grip it, but the more restricted is the movement of our arms by the sides of our bodies and, if too low, by our knees. However, the steering also becomes more precise because it's guided more by the forearms and not the arms. The closer the wheel to us, the easier is our reach, but it might be too close for comfort, so our body restricts the free movement of the arms, or that there is an imminent risk of bashing the wheel in a crash. Also, the lower should the wheel be kept so that it isn't held too high or placed too offset relative to the back angle.
The idea is to use the adjustment to the wheel to bring it closer to us and as parallel to the angle of the back as possible. If you can't reach a sufficient angle, you need to compensate by bring the wheel closer and lower and, if this does not work, change the angle of the back and, if nothing works, change the positioning of the seat as a whole. We also need to try and reach a situation where our hands grip the wheel at 9 and 3, while being lower than our shoulders. For general road driving purpose, a gap of five centimeters is a good compromise. For highway driving, you can set it lower, to a gap of as much as ten centimeters, and for racing purposes it should be just lower than the shoulder itself. You might need to compromise the exact height to ensure proper reach of the wheel and a good view at the instrument panel. Remember that you are still to adjust the seat height.
If you have the choice of the wheel size, keep in mind that a bigger wheel is less comfortable to grip, requires longer motions, but is more accurate. A smaller wheels is more comfortable to grip, heavier to turn, but easier to operate for large steering inputs. A good wheel should be about 5 centimeters tighter than your shoulder width, and change depending on the nature of the track: Tight and winding, or full of long straights.
The seat height is going to change our positioning relative to the controls, our view at the instrument panel and at the road ahead. The higher we are, the better we see. However, we will be less stable and less "at touch" with the car's chassis. The idea is to adjust the seat height to ensure proper reach of the steering and pedals, while opening up the line of sight to the instrument panel and to the road ahead, with the goal of being roughly four fingers away from the ceiling, or five fingers (a hand-width) for racing purposes. You might need to compromise the precise height to ensure proper reach to the controls. You might need to recheck your back rake angle and even the alignment of the wheel.
This is also a good time to use the remaining adjustments to ensure the full options are exploited. Adjust the angle of the seat's base to ensure proper reach of the pedals. The idea is not only to be able to fully depress the pedals and keep the knees bent, but also to keep the thighs supported by the seat as much as possible without being restricted by it. The greater the tilt, the better the support of the seat to our thighs, but too much tilt (or too long a seat's base) and you will find that when you try to full depress the pedals, your thigh presses hard against the seat where it's full efforts should be directed towards the pedals. A good positioning is such where you can fully depress the pedals with the thighs against the seat, but just so lightly that you can wedge your palm between the thigh and seat.
Other adjustments to be used in this stage include the seat's lumbar support and side support. Adjust them to the greatest support possible without creating "pressure points" and without limiting your movements of turning the head, depressing the pedals and moving from pedal to pedal, as well as operating the wheel. Another important adjustment is the pedal configuration, where possible. The adjustment should be such where heel and-toe be easily performed, as will the pivot movement from throttle to brakes. The pedal travel should be long enough to provide accurate braking, but not too long as to bend the knees to 90 degrees when the pedals are unrepressed. The contact between the foot and the pedals should feel secure, even if the foot does not fully cover the pedal.
Checking the adjustment
After we utilized the seat's adjustments to their fullest, we need to check our positioning relative to the wheel. There are several ways to do this. The main way is to put our left hand forward so that it is straight, but not forcefully outstretched. We should be able to place our wrist perfectly over the top of the wheel, without leaning our scapulae forward. The wrist should be placed flat over the top of the wheel, so it can be bent slightly over it. In a car with a stock seat, you might need to be even closer (so your hand is bent during this check) for racing purpose. Another thing to check is that you can quickly turn the wheel from lock to lock without bending forward, or that you can grip the wheel at 9 and 3 and turn it 260 degrees so your forearms cross, and still have the back against the backrest. One last check you can perform is to put your hands crossed over the wheel and ensure that you can do this without locking the elbows.
Restraints and safety
If you use a stock belt, always ensure that the upper mounting is higher than your shoulder and that the strap itself runs directly over your acromion, which is the bony socket between your collar bone and the arm. If it runs over the collar bone (calvicula), it will cause fractures to the bone in a collision, and if it's on the shoulder itself it will slip off of it. It also needs to be placed on the acromion without any gap. The lower part of the belt should fit as low as possible, over the pelvic (and not over the stomach) and be as tight as possible. For racing purpose, you can tighten your belt like a harness by pulling it quickly and than harnessing it, or by bring the seat backwards and downwards, fitting the felt and tightening it, and than pulling it to lock it and lean forward into it as we bring the seat forward and up to the desired position.
It's important to ensure that the airbag in the wheel is roughly pointed towards our chest and head, and has a safety margin of 10 (25 centimeters) or even 12 from the sternum (breastbone). If the seat has an adjustable head restraint, bring it up so that it is at least as high as your eye brows, and preferably higher so that the center of the restraint is at that height. It's just as important to make sure it is as close to that portion of the head as possible, a mere 2-3 centimeters. The adjustment of the head restraint itself might not suffice and it's possible that you will need to bring the whole backrest to a more upright angle to get it right.
If you use a helmet, ensure it has the SA standard, as well as having a clearance from the ceiling and the head restraint, and purchase it with some sort of protection for the neck (such as a HANS device) to ensure the helmet does not hurt your collar bone.
Trucks with steeply angled steering rims, do not allow to adjust a posture as well as we described above. The check for the proper posture in such a vehicle is simply to ensure that the arm can grip the wheel at the top without being fully outstretched and without hounching the shoulders forward. The driving position is a Single-Seater racing car (Formula, Funjo or Kart) is going to be much more leaned, but will also require that no limb be outstretched. The posture used in oval racing (NASCAR being the prominent example) is the direct opposite, being closer to the wheel so that you can grip it less or more statically for long durations of time under constant side forces. You should be able to rest about half of your forearm unto the wheel in such a car. The rim itself is also likely to be bigger.
For more visual illustrations, look here
The driver has four pedals:
In motorsport, several methods of pedal work are used: left foot braking and Heel and Toe and special metal pedal sets are bolted over the orignal ones to enable this, particulaly the heeltoeing technique. However, the driver must ease off of the clutch completly when turning into corners, and squezze his foot against the rest pedal. The reason we treat the rest-pedal as an actual pedal, is because it has two uses:
The right foot should be rested with the heel against the floor, roughly in front of the brake pedal. Th pedal itself should be depressed with the ball of the foot, but you don't necessarily need your whole foot on the pedal. To accelerate, you pivot your foot to the right and depress the throttle. This increases the sensitivity because the pressure is applied against a lower part of the pedal, which makes the required leg motion longer and more sensitive.
The proper grip of the wheel is at 9 and 3 (9:15), with the palms on the outside diameter of the wheel, slightly tilted down so that the heel of the thumb presses against the face of the rim, and with the thumbs hooked inside the wheel and the fingers curled around it and under it's spokes. The width of the wheel, as well as it's texture and that of the gloves (if used) should allow for good contact and allow to maintain this kind of grip. This grip creates the widest leverage between both hands, so they operate as balanced weights on either side of the wheel. Any higher (as in the traditional 10 to-2) would make the hands work like one big hand, so that when you turn right, the weight of both arms acts as a "dead weight" that pulls the wheel further down and right than desired, and we need to activate other muscles to cancel this out. A lower grip (like the newly found 8 to-4 grip I've witnessed) further limits steering since the free movement of the arms is in part obstructed by the sides of the torso.
Adjusting the mirrors for the proper angle is crucial for achieving good all around vision in a glance. The idea is to fully exploit the field of vision that our mirrors can give us by reducing the overlapped areas between the mirrors, while avoiding convex mirrors as much as possible. Fitting a 'wide-angle' convex mirror over your interior mirror is to be avoided. These mirrors are usually the make of inferior far-eastern product that distorts the image, creates unnecessary overlap, displays irrelevant portions of the car's inside (especially in a race car equipped with a roll cage) and can shatter or get thrown about in a collision. The idea is to adjust the stock mirror (which is also shatter-proof) for a full view of the rear window, and than adjust the side mirrors for the smallest possible overlap with it. The key of this is to open up the mirrors so that the sides of the car (the quarter-panels) are no longer seen in them.
To ensure that the adjustment is inch perfect, ensure that a person standing a few meters behind the car and can be seen in the right edge of the interior mirror, can also be seen in the left edge of the right wing mirror, and the same in the left wing mirror. Many cars come with one smaller mirror, usually the passenger's side mirror to the right. This mirror should be opened further out so that you can see a person in an overlapping manner (as described above) in a bigger distance. In most cars, the proper adjustment is normally reached by opening the mirror three or four "steps" out with the electronic adjustment, or by moving the head to the center of the car and opening the mirror so that in this position you can just see the edge of your car, and than open it a bit further out.
The idea is that the driver's eyes, when he takes a glance at the mirror or even slightly tilts his head, is quite wide: Your peripheral vision gets just about everything that is reflected in the front windows, a bit more than 180 degrees. If the side mirrors field of vision is "wasted" by overlapping the field of vision in the interior mirror, we will have considerable blind-spots to our sides, in the 7 and 4 O'Clock hours. If they are opened wider, without creating a significant blind spot alongside our car, we could cover those blind-spots so that any other vehicle overtaking us will be seen in at least one mirror untill it could be seen alongside us in our peripheral vision.
Side convex mirrors can help in road cars in parking manouvers (display the sides of your car) and/or in eliminating the little blindspot between the peripheral vision and side mirrors. Small side-convex mirrors (as opposite to large ones) are relatively effective, and their extended field of vision makes a greater contribution to driver safety than the problems of distortions and repetitive information they cause. On the track, though, they will distorb the car's aerodynamics. In a road car, the smaller mirrors (unlike big mirrors or "Fish-eye mirrors") do not cause this issue.
If you read This article you can notice the author is not observing mirror adjustment correctly at all: Mirrors are adjusted by overlap, not according to the sides of your car (leastways initially). After adjusting the mirrors correctly one can use the edges of the car as reference points for parking/adjusting the mirrors after they were swayed from proper adjustment but not for driving forward, where such reference points are greatly redundant. This response article from me will explain further, why and how the assertion of Eddie Wren is wrong.
Also, the advocated mirror adjustment in the article is slightly too narrow while the opposite example is presented as too wide. The mirrors should always overlap as slightly as possible, so the problems regarding lack of visibility in the rear-view mirror due to habits, car structure and occupants of the rear seats, are greatly irrelevant. Moreover, the article illustrates the importance of overlap, but does not prove it to be better than the extended visual field to the side. The whole disscussion is really more relevant during reversing. However, one must keep in mind that people always drive forward for greater distances, in greater speeds and for greater durations of time (hence more hazards and factors) than reversing, so adjusting the mirror badly for the sake of a bit of reversing is useless. One better use convex mirrors, lean towards the mirrors or readjust them while parking (automatically performed in some cars).
Any wider (a wide view) or tighter (a narrow view) will create considerable blindspots. One must consider the possibility of some of the rearview mirror's visual field to be obstructed or a side mirror be thrown off or out of adjustment. These are not excuses, however, to change the mirror adjustments.