Historically, two nuclear power plant incidents have led to major releases of radioactive isotopes into the environment. In the unfortunate event that such an incident would occur in Sweden, the national emergency preparedness has set-up carborne detector systems which can be used to map radionuclides in fallout affected areas. However, analysing the carborne measurments is not trivial. To investigate how these detector systems behave, a full scale model of a Swedish suburban neighborhood was constructed in the particle transport code SERPENT2. Within this model, detector and car geometries where defined to obtain an estimate of the measurement one would obtain efter different cleanup scenarios with an initial 100 kBq/m^2 ground deposition of the fission product Cs-137.