The engines were started by hand. In the late 30's the German teams introduced external electric starters. There was no parade lap, the cars started direct from the grid.

The faces of the drivers were much more easy to recognize in those days as the drivers only used goggles and small helmets. The cars were also more open and often the driving technique differed a lot between the drivers. It was e.g. impossible to mistake Nuvolari in his bright yellow shirt for someone else. However, with several cars for each team, color codes were introduced by the teams both on the drivers' helmets and on the cars. Because of the rarity of color pictures from the era it is hard to study the color codes but the Mercedes-Benz codes from 1938 are known. The car radiators and helmets were as follows:

Caracciola - white, von Brauchitsch - red, Lang - blue, Seaman - green.

The idea of pit signaling came from INDY 500 and was introduced in Europe by Mercedes-Benz team manager Alfred Neubauer in 1926. In addition to the traditional pit boards a multitude of color coded flags were also often used by the teams. For example a red flag meant run slower, a green flag meant run faster, a white flag with red cross asked the driver to make a pitstop and so on.

The tyre manufactures of those days had no chance to build tyres that could stand the force of 600 BHP cars at full speed. You could say that the cars were faster than the tyres. Therefore the drivers had a wide choice of race strategy. A driver could go very fast and destroy his tyres in 2-3 laps or go slowly trying to save the tyres for the full race distance. It was not unusual in those days to see charges with a driver coming through the field only to fall back a lap or two later.

For the 1937 season Continental supplied the following tyre types for the German cars:

TYPE	SIZE	SECTION	TREAD	USE
"AVUS"	24"	Oval	Smooth	Speed circuits
"Tripoli"	22"	Oval	Smooth	High speed tracks
"Coppa Acerbo"	22"	Flat	Light stud	Medium speed tracks
"Nürburgring"	19"	Flat	Heavy stud	Slow speed tracks

Width was usually 5.5" front and 7" rear.

The praxis was that slower cars kept to the right and was passed to the left. Because of the great dangers involved drivers discipline seem to have been much higher than nowadays. In those days the drum brakes had a hard time to keep up with the forces involved and the drivers usually tried to have some safety margin between the cars so that they did not have to rely too much on hard braking. Note that the driver in front was supposed to give room, even if he was on the same lap. A driver depending too much on blocking or using his "right of line" as it is called nowadays could find himself in trouble! See for example Caracciola in Swiss GP 1936 or Hasse at Avusrennen 1937.

On the longer tracks there was often a second pit at halfway point on the track for tyre changes as the tyres quite often were destroyed suddenly. During the pitstops there were a limit on how many mechanics could work on the car. The number was either 2 or 3. There was no international rule, the local organizers did the selection. The general rule was that the number was 2 for races when no refueling was expected. With refueling the number was 3 but at Tripoli for example the number was always 2. There were different rules for different races, whether the mechanics could push the car to a restart or not. The engine had to be stopped during refueling. Refueling happened at about the same speed as for a modern F1 car, 12 litres/second.

The mechanics had the following functions.

With three mechanics:

#1: Jack up, change left rear wheel, start engine.
#2: Jack up. change right rear wheel, jack down.
#3: Water and new goggles to driver, refueling.

With two mechanics:

#1: Jack up, change left rear wheel, change right rear wheel, start engine.
#2: Jack up, remove hub on right rear wheel, water and new goggles to driver, refueling, jack down.

Note that often only the rear wheels were changed, as it was wheelspin that caused most of the tyre wear.

The choice of fuel was free and each manufacturer and team had their secret mixtures of more or less explosive stuff. Here is an example from Mercedes-Benz:

86.0 % metyl alcohol
  4.4 % nitro benzol
  8.8 % acetone
  0.8 % ether

Sometimes during refueling fuel was spilled over the driver, the liquids involved causing burns and irritation on the skin. The fumes from the cars were sometimes also causing trouble, both to the drivers and to those standing near.

Unlike today when all cars are flagged off as soon as possible after the winner has passed the finish line, in the pre-war era the backmarkers often got some extra time to complete the full laps before the race was definitely over. The time seemed to have changed from race to race but was mostly somewhere between 15-30 minutes. This explains the fact that curious times can sometimes be found in the results lists from this era.

The biggest change to modern rules is that you had to finish to be classified, an engine failure on the last lap could be devastating. This rule lived on into postwar F1 racing. A classic example is the Italian GP 1953 where Ascari, while leading, spun at the last corner on the last lap. As there were only three cars remaining on the same lap as the leader he should nowadays have collected 4 points for a third place, as Frentzen in Brazil 1999. However in 1953 it was Villoresi, a lap behind, who got the third place, and Ascari never appeared in the results.