We present Scout, a configurable source-to-source transformation tool designed to automatically vectorize C source code. Scout provides the means to vectorize loops using SIMD instructions at source level. Our main focus during the development of Scout is a maximum flexibility of the tool in two ways: being capable of vectorizing a wide range of loop constructs and being capable of targeting various modern SIMD architectures. Scout supports several SIMD instructions sets like SSE or AVX and is easily extensible to upcoming ones. In the second part of the paper we present results of applying Scout’s vectorizing capabilities to CFD production codes of the German Aerospace Center. The complex loops used in these codes often inhibit the automatic vectorization of usual C compilers. In contrast, Scout is able to vectorize most of these loops. We measured the resulting speedup for SSE and AVX platforms.