Abend,
ich weiß dies ist ein Problem was recht viele haben, trotzdem hoffe ich das mir jemand hilft.
Wie schon gesagt sind nach einpaar Modinstallationen alle Fahrzeuge weg... Habe nun erstmal alle Mods wieder gelöscht,nur das Problem ist nicht behoben. Ich kenne mich in diesem Bereich nicht wirklich aus,meine mich aber erinnern zu können das man den log.txt braucht,hab jetzt mal rauskopiert,hoffe das geht so. Ist übrigens die Mac version 
GIANTS Engine Runtime 5.0.1 (build date: Oct 2 2013)
Copyright (c) 2008-2012, GIANTS Software GmbH (http://www.giants-software.com), All Rights Reserved.
Copyright (c) 2003-2012, Christian Ammann and Stefan Geiger, All Rights Reserved.
Application: FarmingSimulator2013
Main System
Core(s): 4 @ 1.8 GHZ
OS: Mac OS X 10.9.4
Physics System
Driver: NVIDIA PhysX Runtime
Version: 2.8.4
Thread(s): 2
Input System
Keyboard enabled
Mouse enabled
Gamepad/Joystick disabled
Force Feedback disabled
Sound System
Driver: OpenAL
Version: 1.1
Device: Ausgang (integriert)
Max. sources: 512
Render System
Driver: OpenGL
Card Vendor: Intel Inc.
Renderer: Intel HD Graphics 4000 OpenGL Engine
Version: 2.1 INTEL-8.28.30
GL_NV_texture_compression_vtc not supported
GL_NV_vertex_program2_option not supported
GL_NV_vertex_program3 not supported
max_texture_layers: 8
OpenGL initialization successful
Hardware Profile
Level: Low (auto)
View Distance Coeff: 0.750000
Shadow Quality: 0.000000
Skip Mipmaps: 1
LOD Distance Coeff: 0.750000
Terrain LOD Distance Coeff: 0.750000
Foliage View Distance Coeff: 1.000000
Farming Simulator 2013
Version: 2.0.0.9 RC18
Available Languages: de
Language: de
Game vehicle types loaded
Mod directory: /Users/nicolaiwillig/Library/Containers/com.astragon.farmingsim2013/Data/Library/Application Support/FarmingSimulator2013/mods
Loading shader WAD '/Users/nicolaiwillig/Library/Containers/com.astragon.farmingsim2013/Data/Library/Application Support/FarmingSimulator2013/shader_cache/shader_1_1_1024_1024_OGL_UK_8.wad' ... 534 hashes, 862 shaders, 1082423 bytes compressed
data/sky/sky_day_night.i3d (0.00mb in 37.57 ms)
data/sky/rain.i3d (0.00mb in 3.19 ms)
data/sky/hail.i3d (0.00mb in 0.77 ms)
data/maps/map01.i3d (3.36mb in 5138.72 ms)
dataS2/character/pedestrians/casual08.i3d (0.53mb in 71.57 ms)
dataS2/character/pedestrians/executive03.i3d (0.27mb in 40.90 ms)
dataS2/character/pedestrians/casual07.i3d (0.32mb in 49.72 ms)
dataS2/character/pedestrians/casual03.i3d (0.33mb in 45.04 ms)
dataS2/character/pedestrians/casual02.i3d (0.31mb in 47.37 ms)
dataS2/character/pedestrians/casual15.i3d (0.40mb in 56.11 ms)
data/character/farmer/farmer_player.i3d (1.75mb in 118.62 ms)
data/vehicles/trucks/milktruck.i3d (1.19mb in 221.22 ms)
data/vehicles/cars/car3.i3d (0.39mb in 41.35 ms)
data/vehicles/cars/car2.i3d (0.42mb in 42.23 ms)
data/vehicles/cars/car4.i3d (0.33mb in 29.05 ms)
data/vehicles/cars/car5.i3d (0.37mb in 37.16 ms)
data/vehicles/cars/car6.i3d (0.38mb in 39.28 ms)
AL: error ... Invalid Value
Error: setting source offset with a value of: 1.021000
data/vehicles/cars/car1.i3d (0.43mb in 44.33 ms)
data/vehicles/cars/car7.i3d (0.47mb in 143.73 ms)
Ich schätze mal das irgendwas die vehicle.xml "vernichtet" hat 