Car-following systems aim to improve safety and comfort whereas increasing traffic throughput. These techniques follow a spacing policy that determines how the ego-vehicle tracks its preceding one. This paper proposes a spacing policy to maximize the traffic throughput and reduce the inter-vehicle distances without losing safety and ensuring the string stability. A variable time gap policy is developed for low speeds, yielding the same dynamic response for high speeds and shorter spacing gaps. Simulations and real platforms' experiments are shown to validate the proposed approach.