Flood risks concerned to vehicle�s instability have become more conspicuous and it is thus necessary to understand the behaviour of vehicles exposed to floodwaters. Therefore, this paper aims at investigating the thresholds of vehicle instability in floodwaters at different orientations. A stationary die-cast model vehicle (1:24) was used with the condition of rear tires being locked only, positioned at different orientation angles on a flat road surface in the partially submerged zone. Measurements were taken including the approaching velocities and water depths, through which the instability was computed. The study concludes that a partially submerged vehicle becomes instable at high water depths and low flow velocities and vice versa. Further, the vehicle was observed to be most stable when positioned at orientation angle of 0°/360°, with the limiting depth � velocity (D*V) value of 0.0168 m2/s. On the other hand, it was noted to be least stable when positioned at the orientation angle of 90° and 270°, with the limiting (D*V) value of 0.0144 m2/s. The outcomes from this study were later translated into guidelines. © 2018, Penerbit UTM Press. All rights reserved.