If the IMU is not used for IMU integration corrections, and it is simply being used to measure acceleration and rates of turn from the 3x acceleromoters and 3x gyroscopes, the IMU can effectively be placed anywhere on the vehicle, depending on the focus of the analysis and cable configuration.
Mining users often fit IMU systems to the suspension of the vehicle to estimate G-forces experienced by the tyres.
The IMU has been designed with 6x holes (Ø4.2 mm, No. 8 Thread Size) so it can be fitted with custom mounts, as long as it is mounted flat with the X-acceleration arrow in the forward direction.
Racelogic offer an IMU roof mount (RLACS216), which assists with mounting an IMU on a flat metallic surface, such as a roof.