One of the classic metrics of a car is how fast it can go from 0 to 60 miles per hour (or 0 to 100 kph). E.g, the 2011 Bugatti Veyron Super Sport goes from 0 to 60 in an astonishing 2.4 seconds.
For an automatic, it seems like you could mash the accelerator to the floor and do 10 (or whatever) time trials and then average them. But is it possible you could arrive at 60 mph sooner by depressing the accelerator only a fraction of the way, or by pumping it?
And for stickshifts, isn’t the 0 to 60 speed in part due to the skill of the driver? Does the time trial take into account the correct shift points on the tranny, or is it just get to 60 in as short a time as possible, whatever the gear? What about the weight of the driver? The type and amount of fuel? The relative humidity, etc., etc.? It seems like a lot of variables could affect the outcome.
What’s the straight dope on how these measurements are made?
Techniques like that might have been helpful with mechanically-linked throttles. But all modern cars have electronic throttle control (ETC), i.e. the throttle is controlled by a computer and the accelerator pedal just moves a sensor that tells the computer what the driver would like to do. ETC allows the engine to cope with transients (sudden changes in power demand) better than a mechanically-linked throttle. In a non-ETC vehicle, when you snap your foot to the floor, the throttle plate snaps wide-open, and the fuel system may or may not be able to keep up with the sudden change in air flow, resulting in hesitation or stumble. In an ETC vehicle, the computer can open the throttle plate just a bit more slowly than your foot mashed the throttle down, providing that little bit of extra time for the fuel system to keep up, eliminating any stumble. I can’t see an ETC vehicle performing best by doing anything other than stomping the accelerator to the floor.
Yes, a lot of variables could affect the outcome. The EPA regulates fuel economy evaluation, so there are strict requirements on the test conditions for that. However, the EPA has absolutely nothing to say about 0-60 times, so test conditions could be pretty much anything at all. The FTC may get involved if a manufacturer is simply lying (e.g. their test was done with a non-stock vehicle that had all of the extra seats and carpet removed to trim weight, but the advertised claim was for a stock vehicle), but if you want to do the test with a 75-pound dwarf behind the wheel who is missing one arm and one leg and run the test at or below sea level on a cool day with low-viscosity oil in the engine and gearbox and just a gallon of gas in the tank, there’s nothing stopping you.
Where the limiting factor is tyre-road adhesion, mashing the accelerator to the floor is not going to give you the fastest time. You want to accelerate at a rate where the tyres are almost (but not quite) slipping.
Assuming of course that the car has traction control. Otherwise in any powerful car just mashing the accelerator is going to leave the car approximately where it is while the driving wheels gradually vanish in cloud of acrid smoke.
For what it’s worth, in any sane situation (that is to say, if this statement is wrong you are a professional driver and know this to be wrong and can explain why) the correct shift point for maximum accelleration is going to be the red line.
Yep and I’d bet the kind of expert driver that would be employed to set 0-60 times would turn off things like TC.
I suspect that 0-60 times aren’t a very good metric; any vaguely sporty car can do this very quickly, and slight differences in set up and driver skill may swamp the actual performance difference between two cars of the same class. But it’s part of the public consciousness.
The engine is an air pump. The more air you introduce the more power you can make. Pumping the throttle won’t help lower your times, but depending on a lot of factors not quite full throttle might keep the tires hooked up
The skill of the driver for sure enters into it even with an auto. Most if not all car magazines use the same drivers over and over and take several runs to find the best time. Often they publish the environmental data in the road test.
Weight of the driver isn’t a huge deal IMHO. I weigh 250 you weigh 210. The car weighs 4,000. My extra weight is 1% of the total. Less than the difference between a full and empty gas tank.
Condition of the tires, weather (temp and humidity) are all factors. When doing comparison tests they try to run them under the same conditions. It’s not much use comparing times on a cool morning versus a hot mid-day.
Is this always the case? Or could the max acceleration be a a point below redline. Could you reasonably have a situation where your fastest time to lets say 45 mph would be to stay in 1st gear all the way to 45 which would be redline, but to get to 60 mph your fastest time would be to make the 1-2 shift at 40 mph?
A computer controlled car it doesn’t know your goal is 60, all it gets is fastest acceleration because your foot is mashed on the accelerator and the fastest way to get from 40 to 41 is to stay in gear, shifting would take longer to get to 41 mph, but over the longer haul to 60 the car may make up for it in a earlier shift and accept the shifting penalty earlier then later (but in both cases the car does have to pay the shift penalty at some point)
The correct shift point is NEVER the redline. You’d blow up your engine in no time doing that. Fortunately, most if not all cars have a rev-limiter that prevents you from exceeding redline but it is not always a precise cutoff.
The correct shift point is the torque peak which is much lower than the redline and usually lower than the horsepower peak. Done extremely well, you would shift before that point so that the increase in rpm while clutch is in will bring you to the peak.
For a Bugatti Veyron, the torque peak is at 2200 rpm, but unlike most, it stays flat until 5500rpm. You could shift almost anytime from just above idle and get the same results. Redline is probably 6500rpm.
For a Chevy Camaro, you want to hit the torque peak at 5000rpm +/- 100rpm. Redline is probably also 6500rpm.
Torque = acceleration, horsepower = top speed
0-60 runs use as few gears as possible. Many cars never leave 1st gear. In most cars, a 1-2 shift is straight and therefore fast.
Yes and no. Maximum acceleration is going to come from keeping the engine near its torque peak. Some engines due to design or tuning make peak torque at much lower than maximum rpms with the torque numbers falling off substantially as rpm climbs. Often referred to as a “stump puller” amongst hot rodders and racers. An engine with this kind of power production actually would benefit from short shifting (shifting somewhere just after torque begins to fall, but well before max rpm). However in very short run such as 0-60mph the time lost to making the shift (no power is being applied for some fraction of a second) may negate the gains of short shifting. In a longer run, like a 1/4 mile race it very much can be faster to short shift.
So you’re not really asking how it’s measured, but how does one get the BEST 0-60 time.
The answer is, it depends.
It depends on the specific vehicle, type of transmission and skill of the driver.
By way of example, the way to get the best launch out of a Lamborghini Diablo for instance is to wind the engine up to 5,000 RPM and dump the clutch. Do it right, and all 4 tires squawk once and you’re hurtling down the road. Do it wrong twice and you’ve destroyed the clutch and are looking at thousands of dollars in repair work.
Some newer vehicles have specific technology that assists with doing a good launch. I have a friend with a 2007 Audi A8, with the Lambo v10 engine. It’s an automatic, and there’s actually a particular sequence of steps that you can do to put it into “launch mode” in order to get the best launch. First you put it into Sport Mode, then turn the Traction Control off, then push the brake all the way to the floor, fourth the gas pedal goes all the way to the floor (this takes some finesse to get right) and then to launch you release the brake. Doing this right, has the car revving at around 2-3krpm before the launch, even with the gas pedal floored prior to launch
Change the vehicle to a motorcycle and things get even more complex, because you’re not only talking about finding the perfect balance of throttle and clutch engagement, but you’re also working feverishly to keep the front wheel down so that you don’t flip the bike over.
Maximum instantaneous acceleration in any given gear occurs when the engine is delivering its peak torque. For launches from a standing start, you are best served by having the engine at its peak-torque RPM and letting the clutch out as rapidly as will allow that RPM to be maintained while holding the accelerator to the floor (this assumes no wheelspin). For an automatic transmission, you’d choose a torque converter with a stall RPM somewhere slightly below that of peak torque.
Highest average acceleration between arbitrary speeds V1 and V2 requires keeping the engine as close as possible to maximum power output - an RPM necessarily greater than the peak-torque RPM - for the entire time between those two speeds. You’re trying to increase your kinetic energy as rapidly as possible, and the only way to do that is by having the engine operate at or near the highest possible mechanical power output level. So you upshift when the RPM exceeds peak-power-RPM by some margin, and when you reengage the clutch, your RPM would ideally be below peak-power-RPM by that same margin. Accelerate until RPM is above peak-power-RPM once again, and upshift again.
If you were using a CVT, you’d configure it so that it would launch with the engine at peak-torque RPM and thereafter the engine would operate continuously at its peak-power RPM.
Yes, maximum acceleration is at the torque peak. But you are forgetting the GEARBOX which is ironic when we are talking about shift points!
You need to maximize transmission output torque, NOT crank torque. And in almost circumstances that means take the engine to the red line for max acceleration.
With regards to shifting, it’s all about horsepower, not torque. Torque is essentially power/RPM. At higher RPM, you may be beyond peak torque, but you are turning more RPM so you are doing more work. You should shift at the point where you are making less horsepower at the RPM you are turning then the RPM you would be in if you shifted gears, unless you hit the redline first.
If a motor makes 250lbs of torque at 2500 rpm, and 200 lbs of torque at 5000, you are still better off at 5000 rpm. You are making less power per RPM, but turning twice as many RPM.
In most engines, your best bet is shifting at redline, but not all.
I’ve read magazine reviews where drivers recalled skipping the clutch and just going from one gear to the next. Something to do with cars that share gearboxes with lorries.
I must concede that in a 1999 Dodge Neon 2.0 DOHC, you would be better shifting at redline. The charts are messed up, but you need to shift to 3rd and would be doing 4605 rpm at 60mph. My RPM numbers don’t match those in the article but the point is proven. I’d have to have the transmission ratios and torque curve to test the theorum on a different vehicle.
Both, actually. I was wondering if the manufacturer stipulated some set of conditions for deriving the 0 to 60 time. E.g.,
IF you take Stock Vehicle with fully-loaded curb weight (A) and fuel type (B) and tire specification (C) and atmospheric conditions (D) and <<insert long string of variables here>> and typical driver (Y) shift gears “correctly” (Z),
THEN 0 to 60 mph will occur in 5.2 seconds.
It sounds like the answer to this question is no, this does not occur.
It sounds more like Random Car Magazine has Professional Test Driver and Crew game the system to strain the tolerances of the car in pursuit of blasting out the lowest possible time. Meaning I won’t ever get that Bugatti Veyron to 60 mph in 2.4 seconds, unless I drive it off a cliff.
If you’ve got the cash to get into the car, you probably have the money to go to a few “professional driver” schools. With the flat torque curve of the Bugatti, it would be considerably easier to match the magazine, other cars may be more difficult.
Assuming that you’re doing this with a new car, the magazine testers use the stock tires, so they aren’t a factor. They use pump gas of whatever specification the manual calls for. Not a factor. They state the optional equipment and curb weight, so if yours is the same, it’s not a factor. Some magazines give the atmospheric conditions at the time of the test.
The magazines use cars that came out of the Manufacturer’s press pool. It’s not uncommon to see the exact same car tested by two or more magazines, usually a big one and a lesser known or foreign one. They can’t flog the car all day, they have deadlines and someone else may want the car. So they might make 5 to 10 tries and publish the best or average them out.
You have months to perfect your launch and shifting skills. You’ve got a car that hasn’t been whipped by ten magazines before it got to you. With those advantages, and good weather, you can beat the magazine’s time. Or not. Some individual cars are just stronger than average, and you can never trust that the press cars are “massaged” in order to get better reviews. There have been documented cases of cars getting engines that have been bored out and had a better camshaft.
One thing on the Bugatti though. I’m wondering if they used an official Bugatti driver to do the tests. It costs a million and a half, I imagine they are reluctant to have just any old driver at the wheel.
