This is very short and basic documentation of the vehicle entry syntax 
used in the vehikel.tab file:

Open vehikel.tab with a text editor. 
(The text editor must support unix style newlines.)
It should start with: 

---------------
200 
Bus
strasse
pax
48
0
acht
false
80
500000
0
0

Explanation

200:     Number of basic image. Do not change in v0.74e
Bus:     Name of the thing. Must match entry in language files.
strasse: Kind of way the vehicle uses. Use "strasse" for trucks and bussees,
         "schiene" for trains
pax:     Typ of goods to transport. See other vehicles for other gods.
48:      Max number of goods units carried
0:       Type of smoke, 0 = doesn't smoke, use 76 for diesel and 47 for steam 
acht:    number of sub-images, don't change for trucks. 
         Waggons may use "vier" or "acht" depending on the number of images.
false:   doesn't show freight as image, true for using a diferent image for 
         loaded cars (200+8 in this case)
80:      max speed in km/h
500000:  cost of the vehicle
0:       engine power in KW (unused for trucks)
0:       vehicle weight in tons (unused for trucks)

Change the values to change the bus.
You can change the existing vehicles this way. To include new vehicles
you need to change the depot.tab file. See depot_tab.txt for further 
explanations.

If you don't understand this explanation or if you have questions how to 
include new vehicles into the game just ask me:
hansjoerg.malthaner@gmx.de

Written by Hj. Malthaner, August 2000