Fixed-priority scheduling has been widely used in safetycritical applications. This paper explores the parametric utilization bounds for implicit-deadline periodic tasks in automotive uniprocessor systems, where the period of a task is either 1, 2, 5, 10, 20, 50, 100, 200, or 1000 milliseconds. We prove a parametric utilization bound of 90%+z for such automotive task systems under rate-monotonic preemptive scheduling (RM-P), where z is a parameter de ned by the input task set with 0 ≤ z ≤ 10%. Moreover, we explain how to perform an exact schedulability test for an automotive task set under RM-P by validating only three conditions. Furthermore, we extend our analyses to rate-monotonic non-preemptive scheduling (RM-NP). We show that very reasonable utilization values can still be achieved under RM-NP if the execution time of all tasks is below 1 millisecond. The analyses presented here are compatible with angle-synchronous tasks by applying the related arrival curves. It is shown in the evaluations that scheduling those angle-synchronous tasks according to their minimum inter-arrival time instead of assigning them to the highest priority can drastically increase the acceptance ratio in some settings.