First of all I split the blueprint into 4, Top, Front, Back
and side. Here you can see a screendump I've made in Acdsee.
Fig. 1
When you got all the files you need, you have to get them into
max, and you have to show them as textures. in the menu custumize/preferences/viewports
press configure drivers (This is if you are using OpenGL).
Then set the texturesize to "Match Bitmap as Cloase as
possible" this will if you a nice crisp texture in the
viewport instead of a texture looking like a real low-res image.
Fig. 2
Then make a plane, with the Lenght and Width correspondent to
the pixels size show in Fig. 1
And make sure the "Generate Mapping Coords." is marked,
then you don't have to map it.
Fig. 3
Then go to the Material Editor and make a material with the
Top image in the diffuse slot. Press the "Show Map In Viewport"
(1) Then you can see the texture when you choose to shade the
viewport.
Press also the "Sample Type" (2) and choose the box,
then you can see the texture a bit better.
Final assign the material to the plane by pressing "Assign
Material to Selction" (3)
Fig. 4
Now go back from the diffuse settings, and set the Self-Illumnation
to 100, so its no getting any highlight in the viewport.
Fig. 5
Repeat all the steps above, to make all the sides of the car.
Fig. 6
Now you can start modelling, you can see the start of the mesh
for my Mercedes SLK, the material i'm using is 50% transparent
so I can see both the mesh and the blueprints behind.
Fig. 7
Here you can see the my final SLK and the blueprints besides
it, as you can see its pretty close to a 100% match. Fig.
8 Fig.
9
Fig. 1
Fig. 2 
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
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Fig.
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