Speeding saves less time than you think
Everyone speeds up hoping to gain time. But time and speed have an inverse relationship, not a proportional one — which means the last few mph you push for are exactly the ones that deliver least. Worse: while the time gain shrinks, the risk grows with the square.
1. How much time do you actually gain?
You have a 10-mile trip. Instead of averaging 25 mph, you push and average 37 mph — about 50% faster. How many minutes do you save?
2. The time curve
The formula is time = distance ÷ speed. Because speed is the divisor, the graph is a hyperbola: it drops fast at first and then flattens out almost completely. Drag it and see where speeding up still pays — and where it buys you nothing.
Travel time curve as a function of average speed.
3. The paradox of the same 12 mph
Here's what intuition misses. Adding 12 mph feels like it should always be worth the same — but it depends entirely on where you start. On the same 10-mile trip:
The same 12 mph increase is worth about 26 minutes when you're crawling and under 2 minutes when you're already fast. That's why risky highway passing buys so little: at 62 mph you're already on the flat part of the curve.
While the time gained shrinks with speed, the energy involved in a crash grows with the square of it: at 75 mph the kinetic energy is about 46% higher than at 62 mph. Stopping distance follows the same logic — the reaction part grows linearly with speed, but the braking part grows with the square. Add fuel consumption, which climbs steeply at high speed because of air resistance. In short: you pay far more risk and fuel for each minute saved — and there are very few minutes.
Work out your own trip
Average speed, travel time and trip cost, with the formula explained.
Open the Average Speed Calculator →See also: Trip cost · Speed, distance & time · Lesson: the large pizza wins