Zero To Sixty

If you're into cars, or hell, even if you're not, "Zero to Sixty" is a phrase you hear all the time. It's become such a standard phrase it has worked its way into everyday conversation, and media not even loosely related to automobiles.  Hell, there is (or, err, was) a whole magazine called 0-60.  At least in the United States and the UK, 0-60mph has become the standard measure of acceleration.  But why?  And really, why do we care?

If common sense prevailed, the standard measure of a car's performance would really be it's power-to-weight ratio.  Nothing determines how a car performs in a straight line more directly than how much it weighs, divided by how much power it has.  Why?  Well, a 500bhp vehicle with a 5,000lb curb weight (like, say, a Dodge Ram SRT-10) is not going to be as fast as a 500bhp vehicle with a 1,000lb curb weight (like, say an Ariel Atom 500.)  But why does the power to weight ratio end up as a statistic only nerds care about, while Rihanna raps about how her "ride" (I'm going to say body) does 0-60 in 3.5? (Dang, Rihanna, you're fast.  Also, warning: that song is awful.)

Well, because manufacturers quote power output at the crankshaft.  This is one of the goofiest, most irrelevant things in the whole automotive world.  A 600 horsepower engine sending it's power through a non-locking torque converter, TH400 3-speed automatic, long metal drive shaft, a Detroit locker, and some half shafts isn't going to put anywhere near 600 horsepower to the wheels, where it matters.  At least bhp numbers are more accurate now than they were before 1972, when the SAE switched from gross to net horsepower, meaning before that horsepower was measured without any ancilliaries mounted (power steering, water pump, alternator, A/C compressor, etc.)  Horsepower at the crank (denoted as bhp, or brake horsepower, where a braking load is placed on the crank to keep it at a constant load, and the amount of force required to prevent rising RPM translates to how much power the engine makes) is a cool number, but it really doesn't matter.  Let's take a look at why.

A 2.0L Subaru WRX is rated from the factory at 227 horsepower at the crank.  The original Dodge (Neon) SRT-4 was rated at 215.  So why, then, does a stock 2.0L WRX only put down between 175-185 horsepower at the crank, while Sport Compact Car dyno'd a totally stock Neon at 223 at the wheels?  Variables!  The WRX"s drivetrain has much lower efficiency than the SRT-4's.  It has a gearbox, three differentials, four half-shafts, and two drive-shafts to turn.  There's more friction, and more power is used up overcoming that friction.

The SRT-4's fat wad of turbopower has a shorter path to tire smoke.  It goes through a gearbox, a differential, and two half-shafts.  That's it.  Other differences include how a manufacturer tests their engines to rate their power.  It's been said that Chrysler underrates most of their performance engine's outputs because they test them on the brake dyno in a "worst case scenario" type of situation.  That is, heat-soaked intercooled, high ambient temperature, A/C compressor on, everything that could suck power.

httpv://www.youtube.com/watch?v=XcFwwAlIixQ

So how odd it is to find that a WRX and an SRT-4, at least stock (psht, yeah right) both do 0-60 in about the exact same time: 5.7 seconds, give or take.  Which is why 0-60 times are popular - it adds together the power-at-wheels to weight ratio as well as how much grip the car has, and spits out a real-world number.  Which is why Rihanna raps that she goes from 0 to skank in 3.5, rather than about her power to weight ratio.

So what's the problem here?  Well, for one thing, why sixty?  Back when the US had a national 55mph speed limit, manufacturers quoted 0-50 times.  And why zero?  How many people do you know that are willing to do a high-rpm clutch dump every time they want to go fast?  People actually own their cars and are responsible for repairs, and if you've ever dumped the clutch on a car at high rpm, you know it is not exactly mechanical sympathy.  Also, 0-60 times are usually recorded by large publications.  They get their test cars from the manufacturer.  Do you really think the 224 horsepower Subaru Forester 2.5XT 5-speed runs to sixty in 5.3 seconds, nearly as fast as a 450 horsepower Porsche Cayenne Turbo (double the power, twice the price)?  Or do you think maybe Subaru gave Car and Driver an XT with, say, a more aggressive ECU tune and larger injectors to make themselves look good?  Or maybe Car & Driver just put it in first, spun the motor to the rev limiter, and side-stepped the clutch.  Hey, you'd get a great 0-60 - once or twice before the gearbox exploded.

Going further, the environmental conditions of all 0-60 tests are different.  A car will generally make more power on a cold day, especially a turbocharged one, because the air is more dense.  However, it'll be more prone to tire spin.  So on a hot day, a C5 Corvette is probably faster than a Cobb-tuned STI.  On a cold one, probably not.  I've heard a story of someone putting a mildly modified C6 Corvette (tune, headers, mild cam upgrade) on a dyno on a hot day in July, and putting down 470rwhp.  They put it on again in December with no further upgrades and put down 503rwhp.  Many publications allow a certain amount of roll-out before timing begins; some don't.  A factory hotshoe or "ringer" of a driver will post 0-60 times that only he and God could replicate.  You get the picture.

Some magazines have the wisdom to publish "rolling start" acceleration times, usually a 5-60mph time.  This is a lot more relevant that 0-60, but still a little weird.  Have you ever floored it from a roll in first gear then let off once you shifted out of second?  Why would you do that?  Far more relevant are what magazines call passing times, usually measure in 30-50, 50-70, or a composite of the two.  These in-gear passing times are a lot more relevant.  I don't know about you, but I more frequently wind out my car in second and third gear WOT merging onto the highway than I do trying to get a perfect launch through second gear off a stop light.

Now that we've talked about the why and the whether or not we should care, the question is, what cars hold records for 0-60 times?  Thankfully the internet is rife with resources on this topic, and the results are somewhat astounding.  For reference, an object in free-fall straight down with no aerodynamic resistance (in other words, 1g of acceleration) will accelerate to sixty mph in 2.83 seconds.  Keep in mind these are "production" cars, although the quotes are somewhat necessary for some.

It's a pretty wide list, mainly composed of ultra-high horsepower exotic supercars you'll never see.  (For instance, the Orca SC7 - there are only 7 of those in the world.  A Veyron Super Sport currently runs you $2.43m after the Euro-USD exchange rate.)  The outliers in the group are the Ariel Atom 500, a piece of scaffolding with wheels and a tiny, supercharged race-bred V8.  Oh, and the seemingly mundane 911 Turbo S - a vehicle with year-round usability, great visibility, and not all that much power compared to a lot of the others.  Credit it's four-wheel-drive, rear-engined weight bias for ultimate grip, and the "launch control" feature on it's 7-speed twin clutch automated gearbox for the crazy launch times.  Heck, Road and Track managed a 2.6 second 0-60 time with the same car!  It's interesting to note that you have to go down to 13th place - that'd be 2012 Nissan GT-R with the new 530bhp engine - to get a car that accelerates slower than gravity.  Speaking of GT-R's, this is what it looks like when you use the launch control on a GT-R.  This is apparently a 3.2 second run, or really slow by top ten standards.  Lordy it's quick.

httpv://www.youtube.com/watch?v=qPs49ZBqawU

So, are 0-60 times really all that relevant?  I'd say no.  But every measurement needs a benchmark, and once it's set, it's hard to set a new one.  So when you and your buddy are in the pub and he's saying his Evo IX GSR FQ360 is 0.2 seconds faster to sixty than a Jaguar XKR or Aston DB9, remind him that it's a mostly irrelevant, made-up statistic that no one really cares about.  He probably won't listen, but hey - it's better than hearing someone brag about the most irrelevant statistic - horsepower per liter!  That's a story for another day.