Not all cars have very efficient light-units either. Small, not-so-bright reflectors don't shed much light on the road. And, just as important as light intensity, is how the light is distributed at the road. This is referred to as the light pattern. Again, Saabs have been blessed with way above average light units.

The third source of bad illumination, is the bulb. There is a variety of bulbs to choose from.
Here, Saab is no better than the rest of the bunch, they put in the cheapest bulbs available.

Then there is the matter of charging voltage. Measured on the battery, with engine running at above idle (2-3000 rpm) and normal power-consumers switched on. (heater fan, radio, lights, etc) A low voltage will give a weak, yellowish light. Not all cars fullfill their promises here.

The main reason for this mayhem is production cost. By choosing a smaller wire or a cheaper component, they may only save a few cents per car. But multiply that by the number of cars produced, and it quickly adds up to millions. The size and shape of the headlights are often dictated by designers, who ranges form above function.

One may be mislead to believe that this only regards older cars, and that today's technology has eliminated shady illumination. Do not for an instant think so. Today's cars are not an inch better than they were twenty or thirty years ago. A while ago I upgraded the wiring harness on a 1998 Toyota Hi Ace. The original wires were 0,75 mm² thick.!! (Sorry, thin!). On a 2000 model Volvo S 70 I did, the wires were 1,0 mm². And DKW (Volkswagen/Audi) still haven't discovered relays….

The only area where things have improved over the years, is charging voltage. Today's cars have voltage regulators set to a higher voltage then in the seventies. A very "clever" solution, the light improves, and the extra production cost is NOTHING. (The car needs a voltage regulator anyway)

HOW TO (not) IMPROVE
Occasionally I get questions like:

-"If I put 100 watt bulbs instead of the original 55 w. in my Saab, will that cure my bad lights?"
The answer is NO! There is nothing wrong with 100 w bulbs (save a few legal questions), but the wiring harness will not handle the extra load. The light relay may fry, and the wires may even burn. (Setting the car on fire) Especially on a 99 with four 5 ¾" headlights. (= 400 watt)

-"Will Cool Blue Vision bulbs improve my lights?"
No. We'll get back to that under "bulbs".

-"How about the yellow bulbs?
Yes, if you are driving in heavy rain or snow. We'll get back to that under "bulbs".

-"I've seen an ad in a motor magazine for green and amber bulbs (Piaa?). Will they improve my lights?"
Dont be ridiculous.

-"If I install large auxiliary driving lights on my car, the light will improve?"
Well, yes, but you're forgetting something. This will not help the dip beam (low beam) lights. When you switch from full beam, to dip beam, the area in front of the car will suddenly go dark.
It doesn't really go completely dark, but the difference in light intensity makes it look that way. Your eyes have adjusted to the bright light provided by the auxiliary driving lights, and then you switch them off…

-"My 99 has four H4 lights, all four are on at high beam, but only two of them at dip beam. If I put extra wires between them, all four will be on at dip beam aswell. Then I will have a decent dip beam light?"
Yes, for a while. But you'll end up frying your wiring harness. Four 55 w bulbs is 220 w. On the 99 lights relay, it says: MAX 150 W. Then there is the small matter of legislation. No country I've heard of (Europe or USA) allows more than ONE pair of dip beam lights. This means that in a periodic vehicle control, the constabulary will tell you to disconnect the extra dip beams. Back to square one…

THE REAL CURE
If you're not satisfied with the original lights, you may consider installing extra light units, such as auxiliary driving lamps, or foglights. Perhaps you'd like to swap your original light units with different, more effective units.
But before you even THINK of putting extra units on the car, start upgrading the existing lights.
Then, if you're still not satisfied, add extra lights. The Gas Discharging Lights (Xenon) does not need thicker wires, due to less current draw. We will look at them later.

The FIRST step towards brightness, is a proper wiring harness.
To eliminate voltage drop at the headlights, thus enhancing excisting light units, it is necessary to install a completely new wiring harness. This includes a fusebox, fuses, proper wires, relay sockets, relays, connectors, and some other small thingies.
The key word here is SHORT, THICK wires.

Somewhere near the battery or alternator, the fusebox must be installed. Preferrably between the battery and the nearest headlight. Bridge the input side of the fusebox, (connect the input terminal of all fuses together) and connect two 6 mm² wires from the bridge to the battery + terminal. Or alternator + terminal.
At this point, you've of course disconnected the battery ground wire. (No need for me to tell you that…..?)

Snap together as many relay sockets as required, (one for dip beam, one for full beam, one for fog, etc) and put them in a convenient place between the fusebox and the nearest headlight.

On my 99 I placed them on the RH lower headlight bracket. Connect one
6-mm² wire from each relay socket input (terminal 30), to the fusebox output. Use relays with twin 87 (output) terminals, and connect one 6-mm² wire from each relay socket output, to each bulb.

To operate the relays, connect a thin (0,75mm²) wire from each relay socket terminal 85, to ground. Then, using the original wiring harness on the bulb plug (which is cut away and disposed) connect the dip beam wire to terminal 86 on the dip-relay-socket. And the full beam wire to terminal 86 on the full-relay-socket. If aux driving lights or foglights is installed, install switches and wires according to its wiring-scheme, and connect their wires to terminal 86 on their relay-socket. Insert the relays in the sockets, put the fuses in the fusebox, and switch on the light. PRESTO! If the car does not explode or catch fire (and there's light) you've done it correctly.

Are we finished now? NO! The power does not come from the battery, it's supplied by the alternator. Remember what I said about feeble wiring harnesses? That also applies to the wires from the alternator to the starter-motor. (The one from the starter-motor to the battery is usually ok. At least for light-supply) And on Saab 99's there is a supply wire from the alternator to the original fusebox. According to the wiring-scheme, these ones are 4 mm² thick. Do not cut them away, but add one or two 6 mm² wires.

CHARGING VOLTAGE.
On Saab 99's with B-engines up to mid 1978, the voltage regulator is attached to the RH front rail, under the battery. Later B-engines and all H-engined cars, has the regulator integrated with the brushes, and screwed into the alternator. They are both electronic, pre set, and sealed. (Older cars have an adjustable mechanical regulator, I won't even bother to write about those) They both have a stamping that states "14V", although this is not always the case. Actually, the ideal charging voltage is 14,3V or more, but in reallity the cars seldom perform more than 13,7V. The easiest way to increase charging voltage is to buy a regulator with a higher voltage setting.

VOLTAGE REGULATORS, SAAB 99.

Other regulators can also be used, but this is as far as my Bosch catalogue goes.

A Mercedes W123 I once had, was equipped with a Bosch alternator with an integrated regulator, stamped 14V. A quick inspection with a FLUKE voltmeter, reveiled 13,4V. (This is not uncommon for Mercedes) The cure was a non-original regulator, stamped 15V. Now, I had 14,1V at the battery. Go figure!

VOLT vs LUX
An unscientific, but nevertheless thorought test was performed with a lightunit placed 25 meters away from a lux-gauge. These results emerged:

10,2 Volts may not sound like much, but I think you'd be surpriced if you found out how many cars that actually has ten-point-something volts, measured at the bulb. I once had a Vauxhall VX4/90 with only 10,3 V at the bulbs. Then I installed a proper wiring harness, which resulted in a healthy 14,3 V. According to the numbers above, my light output was tripled!

One funny thing with electronic voltage regulators is that the output, measured at the battery, seems to be a concistent 0,6 V lower than what's stamped on the back of the regulator. In other words, a 14,1 V regulator gives 13,5 V, whereas a 15 V regulator resulted in 14,4 V. I'm sure there is a locical explanation somewhere, but I somehow fail to see it. For those in the know, some diodes gives voltage drops of 0,6 V, but i really cant see the connection...