This is another Q&A from Yahoo! Answers which I could not stay away from. The question was asked by “pigpigletpoker” and has already received two answers.
Dave_Stark said:

Make a chromatogram of the paint found on the other car involved in the accident.
Then do a side-by-side chromatogram of the red paint from the two suspect cars. Unless they have identical paints, the chromatograms will be different in some way, and you’ll be able to match the suspect auto to the target paint.

Though the concept is scientifically sound – simply compare chromatograms because they should be unique for each paint; however, the “making” of a chromatogram of paint could be a lot more challenging than it seems. What chromatography are we talking about? Gas, ion or liquid chromatography?

Stacey suggested a different approach citing “Analytical Chemist” as the source of information:

Inductively coupled plasma mass spectrometry (ICP-MS) using depth profiling can be used to differentiate between two red cars by measuring the trace elemental composition of the layers of paint on two cars. Paint from different manufacturers will contain different components in trace levels and by measuring the components of each layer of paint the fingerprint is much more varied and precise for matching. It becomes very difficult if the two cars are the same make, model, year and color because the spectra would be very similar and variations in lot might not be enough.
Once you had the spectrum of the violating car it would then be a matter of matching it to the vehicle. There are a number of growing databases that can give you the make and model for a specific signature, making catching the violator that much easier.

Examining layers of paint for trace elements by ICP-MS will definitely get the job done, and this method is currently employed by forensic labs. However, there is still one problem, the question was “how would you use chromatography“. Neither ICP nor MS are chromatographic methods, they are both spectrometric instruments.

There are three basic ingredients in automotive paint: resin, pigment and solvent – all organic compounds. So I would use Gas Chromatography Mass Spectrometry (GC-MS) to profile the car paint chips, and would then either use the database as suggested by Stacy or use the comparison of suspects’ chromatographic profile to the traces found on a victim as suggested by Dave_Stark. The sample prep could be a pain in the neck but that’s a different question.

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