James Gilbert/Getty Images Racing may be focused on driving as quickly as possible, but there are crucial moments when speeds need to be limited for the safety of people exposed to high-performance traffic. Today, every top-level championship imposes pit road speed limits. Drivers in the NASCAR Cup Series have the added complication of not having a speedometer in their cars. Despite ditching analog gauges for a digital dash, the stock car racing body refused to let drivers see their speeds directly. NASCAR drivers have to use the information that they do have and a little bit of practice to ensure that they don't speed on pit roads. The tachometer and gear indicator are the pertinent instruments for completing this task. The engine's rpm, the gear ratio, and the wheel size are enough to calculate how fast the car is moving. However, the drivers aren't crunching these numbers in their heads every time they pull down pit road. Before 2016, the crew chief and the team's other engineers would do necessary calculations at the start of the race weekend, then remind their drivers of the correct gear and rpm before stops. In 2016, NASCAR mandated that Cup Series teams (Sprint Cup Series teams at the time) use customizable McLaren-built digital dashboards, and drivers today monitor a light system or numerical tachometer display for pit speed reference. The light systems are generally favored, as they require less attention. If you've ever played the NASCAR segment of iRacing's simulator, you'll similarly find visual supportive elements, including a pit speed limit bar at the top of the screen. Having a speedometer wouldn't change anything Meg Oliphant/Getty Images Even if NASCAR allowed speedometers tomorrow, it's highly unlikely that any team would drop their current procedure. The sheer precision of the current system can't be beat, as the calculations are accurate down to 0.01 mph. Similar to Formula 1, NASCAR doesn't monitor pit road speed on a moment-by-moment basis. Race officials divide the pit road into numerous sections and measure each average driver speed through the section via car-mounted transponders and electronic timing loops beneath the pavement. Still, Formula 1 differs from NASCAR in that there is no buffer for exceeding a pit speed limit. NASCAR gives drivers a 5-mph buffer. Rules for NASCAR pit speeding were unfortunately written in blood. During the season-ending 1990 Atlanta Journal 500, Ricky Rudd locked his brakes and slammed into two crew members servicing Bill Elliott's Ford. Rudd's Chevrolet hit and pinned tire-changer Mike Rich between the cars. The crash crushed Rich's chest wall and lungs, killing him. At the time, there was no speed limit on pit road. NASCAR imposed a speed limit in 1991.