The paper presents some recent experimental results concerning tracer gas diffusion within the near wake of a simplified model car. The model car is an Ahmed model (with a rear slant angle of 5 degrees, 25 degrees or 40 degrees). Pollutant emission is simulated using heated air injected through a small pipe at one side of the model base. Fine cold wire thermometry is used to measure instantaneous temperature excess in the near wake. Characteristics of the mean and fluctuating temperature fields are presented for the near wake (0 < x* < 10) where x* is the distance x downstream from the model normalized by the model height H. Results are explained accounting for the velocity field. (c) 2006 Elsevier Ltd. All rights reserved.