This is the standard reference on the subject, but out of print.
Published in 2002, ISBN 3-613-02211-7.
It has almost 400 pages and shows cars from more than 100 manufacturers.
If you can't see the radiator identification is almost impossible, but even if the radiator is visible in a picture you might id the maker but to find a precise match of model is great luck.
At that time manufacturers usually built the frame and the body might come from elsewhere so there is a great variety of details.
Dimensions are very basic, wheelbase and track, so for a model find a photo taken from the side, use the wheelbase for scale and guess everything else until it looks right.
A drawing of an Austrian car can be found here:
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