Maintaining a safe distance from the vehicle ahead is critical for safe driving. While LiDAR sensors can be used for distance measurement, their high cost and the large number of vehicles without such sensors—especially in developing regions—necessitate a low-cost yet effective alternative. To address this, we introduce CarVision, a system that utilizes a commercially available single-chip mmWave radar mounted on a car’s dashboard for vehicle ranging. CarVision detects vehicles within the radar’s field of view (FoV) and computes both the distance and relative speed of the vehicles in front. Our system employs a novel hybrid vehicle detection and tracking approach, combining deep neural network-based detection with range tracking in a streamlined pipeline to optimize accuracy and speed. Additionally, we’ve developed a smartphone-based alert system that warns drivers if a vehicle approaches within a critical distance (approximately 2 meters). CarVision demonstrates reliable ranging performance in daytime and nighttime conditions, with accurate measurements up to 50 meters.