https://supercarspeed.com/Independent coverage of how car performance is measured: acceleration, top speed, lap times, power and weight, braking and grip, and electric performance. Every figure is sourced, and every test method is explained.en https://supercarspeed.com/acceleration/awd-rwd-launch-advantage/https://supercarspeed.com/acceleration/awd-rwd-launch-advantage/All wheel drive can use the whole car as ballast, which is worth up to a second to 100 km/h. Above the traction limit speed the advantage becomes a weight penalty instead.Acceleration https://supercarspeed.com/acceleration/factory-claims-versus-tested-times/https://supercarspeed.com/acceleration/factory-claims-versus-tested-times/When a magazine beats the factory figure, it is usually the timing convention rather than the driver. When the factory beats the magazine, it is usually the conditions.Acceleration https://supercarspeed.com/acceleration/gearshift-time-acceleration-cost/https://supercarspeed.com/acceleration/gearshift-time-acceleration-cost/A dual clutch shift interrupts drive for 20 to 100 ms, but the real cost is the speed lost during it. Two shifts to 100 km/h are worth roughly a tenth, and the ratio choice is worth more.Acceleration https://supercarspeed.com/acceleration/launch-control-traction-management/https://supercarspeed.com/acceleration/launch-control-traction-management/Launch control does not eliminate wheelspin, it targets about 10 to 20 per cent slip because that is where a tyre grips hardest. Its real product is repeatability, not a single quick run.Acceleration https://supercarspeed.com/acceleration/one-foot-rollout-explained/https://supercarspeed.com/acceleration/one-foot-rollout-explained/Rollout is the 305 mm a car travels before the timer starts. It is a drag strip convention, it is not cheating, and it changes a published 0 to 60 time by up to 0.42 s.Acceleration https://supercarspeed.com/acceleration/quarter-mile-trap-speed/https://supercarspeed.com/acceleration/quarter-mile-trap-speed/Elapsed time rewards a good launch. Trap speed only rewards power against weight, which is why it is the honest half of a drag strip slip and reveals a car's real output.Acceleration https://supercarspeed.com/acceleration/rolling-start-versus-standing-start/https://supercarspeed.com/acceleration/rolling-start-versus-standing-start/A 100 to 200 km/h time removes tyres, launch technique and surface from the measurement, which leaves power against weight and drag. It is the cleanest engine test a road can give you.Acceleration https://supercarspeed.com/acceleration/temperature-tarmac-acceleration-effect/https://supercarspeed.com/acceleration/temperature-tarmac-acceleration-effect/Twenty degrees of air temperature costs a naturally aspirated engine 6.5 per cent of its power. The surface it launches from is worth more than that, and neither appears in the headline.Acceleration https://supercarspeed.com/acceleration/traction-limit-acceleration-physics/https://supercarspeed.com/acceleration/traction-limit-acceleration-physics/Below 100 km/h a car is limited by tyre grip, not power. On a road tyre an all wheel drive car cannot use more than about 585 hp, and everything above that is stored for later.Acceleration https://supercarspeed.com/acceleration/zero-sixty-versus-zero-hundred/https://supercarspeed.com/acceleration/zero-sixty-versus-zero-hundred/60 mph is 96.56 km/h, and American tests start the clock one foot off the line. Those two conventions together separate the same car by three to six tenths.Acceleration https://supercarspeed.com/top-speed/air-density-altitude-top-speed/https://supercarspeed.com/top-speed/air-density-altitude-top-speed/A naturally aspirated car has almost the same top speed at 3,000 m as at sea level, because thinner air removes power and drag in equal measure. A turbocharged car gains 10 per cent.Top Speed https://supercarspeed.com/top-speed/downforce-versus-top-speed/https://supercarspeed.com/top-speed/downforce-versus-top-speed/Downforce is produced by turning air, and turning air makes drag. A wing that gives 300 kg at 250 km/h can cost 25 km/h of top speed, which is why fast cars learned to fold theirs away.Top Speed https://supercarspeed.com/top-speed/drag-equation-top-speed/https://supercarspeed.com/top-speed/drag-equation-top-speed/Drag force rises with the square of speed and the power to overcome it with the cube. Doubling top speed needs eight times the power, which is the whole economics of a hypercar.Top Speed https://supercarspeed.com/top-speed/electronic-speed-limiter-250/https://supercarspeed.com/top-speed/electronic-speed-limiter-250/The 155 mph limit is not a law and not an engineering limit. It is an informal agreement between BMW, Audi and Mercedes to head off an autobahn speed limit, and Porsche never joined it.Top Speed https://supercarspeed.com/top-speed/frontal-area-drag-coefficient/https://supercarspeed.com/top-speed/frontal-area-drag-coefficient/A drag coefficient without a frontal area cannot be compared between cars. A saloon at Cd 0.28 can push more air than a sports car at Cd 0.33, because area is the other half of the term.Top Speed https://supercarspeed.com/top-speed/gearing-limited-versus-drag-limited/https://supercarspeed.com/top-speed/gearing-limited-versus-drag-limited/A drag limited car runs out of power in top gear. A gearing limited one hits the rev limiter first. Most fast cars reach their maximum speed in an intermediate gear, not the tallest one.Top Speed https://supercarspeed.com/top-speed/three-hundred-mph-barrier/https://supercarspeed.com/top-speed/three-hundred-mph-barrier/Going from 250 to 300 mph needs 73 per cent more power, tyres nobody sells and about 9 km of road. Only one car has passed it, in one direction, as a modified prototype.Top Speed https://supercarspeed.com/top-speed/top-speed-testing-venues/https://supercarspeed.com/top-speed/top-speed-testing-venues/A 490 km/h run needs about 8 km of road before the timing lights and room to stop afterwards. That requirement is why the same handful of venues appears behind every record.Top Speed https://supercarspeed.com/top-speed/two-way-average-record-rule/https://supercarspeed.com/top-speed/two-way-average-record-rule/The Agera RS ran 284.55 mph one way and 271.19 mph the other on the same closed road. That 13 mph spread is why a single direction figure proves nothing about a car.Top Speed https://supercarspeed.com/top-speed/tyre-speed-rating-limits/https://supercarspeed.com/top-speed/tyre-speed-rating-limits/H is 210 km/h, V is 240, W is 270 and Y is 300. Above that the rating goes in brackets. The letter is a certified limit at rated load, and it often arrives before the engine does.Top Speed https://supercarspeed.com/lap-times/driver-variance-lap-times/https://supercarspeed.com/lap-times/driver-variance-lap-times/On a 20.832 km lap, a tenth of a second lost in each of 70 corners is seven seconds. Driver variance is the largest uncontrolled variable in any lap time comparison.Lap Times https://supercarspeed.com/lap-times/gps-timing-versus-transponder/https://supercarspeed.com/lap-times/gps-timing-versus-transponder/A 100 Hz GPS logger resolves speed to 0.1 km/h and distance to under 50 cm per kilometre. That is why record attempts are timed by GPS and why an uncorroborated GPS claim still collapses.Lap Times https://supercarspeed.com/lap-times/hockenheim-laguna-seca-benchmarks/https://supercarspeed.com/lap-times/hockenheim-laguna-seca-benchmarks/A short circuit rewards a different car from a 20.832 km one. Lap length, corner count and average speed decide which car wins, which is why benchmark circuits are not interchangeable.Lap Times https://supercarspeed.com/lap-times/nordschleife-lap-length-confusion/https://supercarspeed.com/lap-times/nordschleife-lap-length-confusion/Records are now timed over the full 20.832 km. The older 20.6 km figure leaves out about 200 m at T13, so times measured on the two distances cannot be compared at all.Lap Times https://supercarspeed.com/lap-times/nordschleife-record-verification-rules/https://supercarspeed.com/lap-times/nordschleife-record-verification-rules/A notary supervises, calibrated equipment times it and a neutral testing organisation documents the car's standard condition. But series-production scrutineering is not required for every category.Lap Times https://supercarspeed.com/lap-times/power-versus-downforce-circuits/https://supercarspeed.com/lap-times/power-versus-downforce-circuits/Downforce scales with the square of speed, so it is worth nine times as much in a 300 km/h corner as in a 100 km/h one. That single relationship sorts circuits into two families.Lap Times https://supercarspeed.com/lap-times/production-car-definition-records/https://supercarspeed.com/lap-times/production-car-definition-records/There is no single definition. The Nürburgring exempts prototypes from production scrutineering entirely, so the phrase in a headline is usually doing more work than the rules behind it.Lap Times https://supercarspeed.com/lap-times/simulation-versus-real-lap-time/https://supercarspeed.com/lap-times/simulation-versus-real-lap-time/A lap simulation is only as good as its tyre model, and the tyre model is the part nobody can derive from first principles. Simulation predicts differences well and absolute times poorly.Lap Times https://supercarspeed.com/lap-times/track-temperature-lap-time/https://supercarspeed.com/lap-times/track-temperature-lap-time/Track temperature moves grip, engine power and brake behaviour at once, and it is rarely in a record announcement. It is worth more lap time than most of the differences being reported.Lap Times https://supercarspeed.com/lap-times/tyre-choice-lap-time-delta/https://supercarspeed.com/lap-times/tyre-choice-lap-time-delta/A track focused tyre is worth more lap time than most engine upgrades, and it fades. Michelin measured 2.9 s per lap over a 6.277 km reference, with most of the gain on lap one.Lap Times https://supercarspeed.com/power-weight/drivetrain-loss-wheel-horsepower/https://supercarspeed.com/power-weight/drivetrain-loss-wheel-horsepower/The 15 per cent rule is wrong. A good manual gearbox is over 99 per cent efficient and a hypoid final drive over 98.5, so real mechanical loss is nearer 2.5 per cent.Power and Weight https://supercarspeed.com/power-weight/dyno-correction-factors-explained/https://supercarspeed.com/power-weight/dyno-correction-factors-explained/SAE J1349 corrects to 99 kPa and 25 C, DIN 70020 and ECE 85 to 101.3 kPa and 20 C. Same engine, same day, 1.4 per cent apart before anybody touches anything.Power and Weight https://supercarspeed.com/power-weight/hybrid-boost-combined-output/https://supercarspeed.com/power-weight/hybrid-boost-combined-output/An engine peaking at 7,000 rpm and a motor peaking at 3,000 never make their maxima at the same moment, so system power is always less than the sum of the two headline numbers.Power and Weight https://supercarspeed.com/power-weight/kerb-weight-versus-dry-weight/https://supercarspeed.com/power-weight/kerb-weight-versus-dry-weight/European type approval defines mass in running order as the car with 90 per cent fuel and a 75 kg driver. A dry weight contains none of that and can sit 150 kg below it.Power and Weight https://supercarspeed.com/power-weight/power-weight-ratio-calculation/https://supercarspeed.com/power-weight/power-weight-ratio-calculation/Power per tonne predicts acceleration above the traction limit and says nothing below it. Which weight you divide by can move the answer by 15 per cent on its own.Power and Weight https://supercarspeed.com/power-weight/ps-versus-hp-versus-kilowatt/https://supercarspeed.com/power-weight/ps-versus-hp-versus-kilowatt/500 PS is 493 hp and 368 kW, and the difference is a unit rather than a rounding error. The measurement standard behind the figure shifts it by another 1.4 per cent.Power and Weight https://supercarspeed.com/power-weight/specific-output-per-litre/https://supercarspeed.com/power-weight/specific-output-per-litre/The Mercedes-AMG M139 makes 155 kW per litre, the first road car engine past 200 hp per litre. Higher specific output than the W16 in a Chiron, from a 2.0 litre four.Power and Weight https://supercarspeed.com/power-weight/torque-versus-power-acceleration/https://supercarspeed.com/power-weight/torque-versus-power-acceleration/Power accelerates the car. Torque only tells you what a gear can do with it. Because gearing multiplies torque and cannot create power, the argument has a definite answer.Power and Weight https://supercarspeed.com/power-weight/unsprung-mass-performance-effect/https://supercarspeed.com/power-weight/unsprung-mass-performance-effect/A kilogram in a wheel has to be accelerated in a straight line and spun up at the same time, so it costs roughly twice what a kilogram in the body does. Then it also has to follow the road.Power and Weight https://supercarspeed.com/power-weight/weight-distribution-handling-balance/https://supercarspeed.com/power-weight/weight-distribution-handling-balance/A rear engined car at 61 per cent rear launches 0.91 s quicker to 100 km/h than a front engined one at 48. What helps traction hurts braking, so 50:50 is a compromise, not an optimum.Power and Weight