You are proposing a short cut that should not be taken. An experimental modal analysis (of an object) should only be compared (for validation purposes) with the computational modal analysis of the same object. I sincerely hope no one provides the information you seek.

I have some paper treated with frequency modeling for human parts

. You see my papers in this field from my page

The modal frequencies of different vehicles depend upon their structure and mass which may be quite different. Hence can't be compared with your FE model. You have to conduct a shake test (ground vibration test) on the vehicle to found its natural frequencies.

Christoforo and Anup are absolutely correct. I could not have said it any better myself.

@Eric Ancich : thanks for you comments.

you're right I've to find the van which i'm studying but i needed some modal analysis of same van car just to see the type of its modal shapes and range of modal frequencies.

From some of the bridges we tested (1,500 Plus) ,A ford statesman was 4 Hz, T-44 truck was 6 Hz our 10 ton truck is 8 Hz (all +/- Hz) . Using FE analysis to get the frequency of a vehicle is over kill. the Van would a simple 2 degree of freedom model. a simple spring and dash pot mass model would give it to you. There is a simple BASIC programming book which has a worked example in it. If I could find it I would post the code for you.