We present a data-driven formant model and methodology for discovering its parameters, namely phoneme targets and coarticulation functions for consonant-vowel-consonant (CVC) words from fully-automatic formant data. The model uses formant targets that are speaker dependent, but independent of speaking style and phonemic context. We used a global error measure to search for optimal formant targets for all phonemes, including classes of sounds where formants are not directly observable. Analysis of coarticulation parameters found significant differences in parameters between clear and conversational speech. Estimated formant targets were largely in agreement with acoustic-phonetic expectations. An intelligibility test validated that resynthesized CVC words using modeled formant trajectories were nearly as intelligible as resynthesized CVC words using observed formant trajectories.