The Laplacian model is the standard distribution for correlation noise estimation at the turbodecoder in Wyner-Ziv coding schemes. In practice, this hypothesis is not always satisfied and, regularly, the estimated model sensibly differs from the error distribution. In this work, we prove that using a model better fitted to the true distribution improves the performances, and we thus propose to use the more general exponential power distribution (EPD) which has never been tested in a distributed video coding context. Gains in rate-distortion over the Laplacian model are illustrated by results on several video sequences, showing that the EPD model outperforms the Laplacian one in off-line (oracle) as well as in on-line (practical implementation) modes. These results also indicate that, in some cases, the on- line EPD model reduces the bitrate even over the off-line Laplacian model.