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How to performed modal analysis on a vehicle model in adams car?

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Methodology: 
The modal analysis is performed on in built MDI Demo vehicle using different four methods.
Results and method description is attached in ppt file.
Methods:
Method 1: Running static euilibrium interactive simulation, after getting .acf file , following line is added in .acf file ‘’ LINEAR/EIGENSOL, NODAMPIN, COORDS=1, 100, KINETIC=1, 100, STRAIN=1, 100, NAMES, TABLE_PRECISION=4” after that simulation is run using .bat file.
Method 2: Running static euilibrium files only simulation, after getting .acf file , following line is added in .acf file ‘’ LINEAR/EIGENSOL, NODAMPIN, COORDS=1, 100, KINETIC=1, 100, STRAIN=1, 100, NAMES, TABLE_PRECISION=4” after that simulation is run using .bat file.
Method 3: Analysis is run using static equilibrium, Linear box check and No damping
Method 4: Static equilibrium is performed, .acf script file used to performed modal using vibration analysis.
 
Questions: 
In every analysis mode frequency and mode number is changed. In some analysis some frequencies are added while in other they are missing. 
Why this is happening? 
Which method is correct for modal analysis?
How to obtain strain energy, kinetic energy while using Adams Linear method for modal analysis?
This results are confusing so that we are getting different results on our own vehicle model. Please suggest correct method. 
Please explain correct method for doing Modal analysis in Adams Car.
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    Frequencies pop up and disappear between runs when you change parameters in the model. Very normal.
    When a eigenvalue is underdamped, the poles to that solution can be written (a-bi) and (a+bi). One frequency and one damping. Once it get overdamped, there are two frequencies, both of them with damping > 100%. So now you got from one frequency with damping to two frequencies without damping. Compare with the solutions of quadratic equations.
     
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