See the Light
Kevin Smith editor-in-chief
Driving the new Lotus Elise for the story in this issue brought the whole subject of mass-and more especially the lack of itinto sharp focus. Every dynamic move an automobile makes, whether it's to accelerate, brake, or change direction involves managing mass.
From a standstill, the engine has to overcome the static inertia of the car as well as the rotational inertia of the wheels (you sure you want those 22s?). Everything has to be spun up, shoved off, and started down the road, and it all takes power. Stopping is the same, with the car's weight and, again, rotating masses attempting to maintain their progress, Cornering is all about convincing the vehicle's mass to deviate from its current heading, something it'll always resist. The more mass there is, the more doggedly it defends its Newtonian right to continue doing what it's doing instead of accepting the change you're asking for.
So whatever you're going to want a car to do (short of crash into a bridge abutment or semi truck), it'll do it better and more happily if you saddle it with less weight.
The designers and engineers at Lotus certainly understand this. Founder Colin Chapman was famous, some would say infamous, for pulling weight out of his race cars so determinedly that durability, and driver safety, could slip down the priority list. The
Elise (which obviously meets all applicable safety and crashworthiness regulations) beautifully exemplifies what a dedicated weight-control program can do for a road car. It's responsive, balanced, quick, and communicative in ways no amount of clever technology could deliver, thanks to the natural athleticism of light weight.
There's a cascading effect in mass control. A lighter, less powerful engine puts less stress into a car's structure and can be accommodated by lighter bits everywhere. That weight reduction further lowers stresses, allowing, for instance, smaller tires and wheels to do the traction job. And they can be controlled by lighter pieces, and the whole thing spirals down into a marvelous state of low mass, where agility improves, efficiency goes up, and even that humble engine can deliver sparkling acceleration. Can you think of any other car, besides the Elise, that can promise 0-to-60-mph times under five seconds, with a mere 190 horsepower doing the motivating?
Light definitely makes right.
Yet light weight doesn't come free or even cheap. Anything, from the tiniest bracket to a complete unit-body structure, costs more to make light than it does to make heavy. Engineering time, materials, fabrication techniques-all those measures that can help trim weight inevitably add cost. Aluminum is lighter than a like-size lump of steel, but it's also more expensive to procure and to form into a useful part. Titanium is more wondrous yet, with a spectacular strength-to-weight ratio, but it's costly to buy and challenging to weld or machine. So you can only take advantage of lightness where you can justify the cost increase.
Thus, price and weight will generally move in opposite directions, one going down only if the other is allowed to go up. And that means an object's price per pound-not something we usually consider unless we're buying ground beef-will tell us something about its technical sophistication: Few dollars and lots of pounds means not much has been invested to optimize performance, whereas spending a pile of bucks to shave a little mass shows a willingness to shoot for the best. And the dollar cost per finished pound will soar.
I'm no math wiz, but I can divide a suggested retail price by a curb weight to determine the price per pound of a car. Or of anything else. I offer the accompanying table for your amusement. I've arrayed an assortment of motor vehicles by price per pound and thrown in a few oddities for reference.
Though published retail prices are complicated by market forces and don't purely reflect the level of a car's technology, overall, I submit that these vehicles generally grow more clever, more tricky, and more capable as you progress down the list. There's a greater concentration of sheer stuff per unit weight crammed into the products near the bottom, where higher prices promise to support a more ambitious reach for perfection.
Not that an exquisite, California-grown avocado isn't sometimes as good as life gets. But there's no denying it embodies a less ambitious technology investment than a Mach 2.5 fighter. Or a feather-light mid-engine British roadster.
|price||weight||price per pound|
|wonder bead, thin sliced||3.29||1.5||2.19|
|Kia Rio four door||10,280||2403||4.28|
|Sony 32 inch TV||900||174||5.17|
|Mazda 3 four door||14,200||2692||5.27|
|Ford F150- Flareside||26,120||4980||5.32|
|Motor Trend (May 2004)||3.99||.07||5.70|
|Toyota Corolla LE||15,295||2524||6.06|
|Honda Accord EX||23,790||3360||7.08|
|Mazda MX5 Miata||22,388||2387||9.38|
|Subaru WRX STi||31,670||3263||9.71|
|BMW M3 coupe||48,795||3415||14.29|
|Mercedes Benz E500||58,045||3812||15.23|
|Porsche Carrera 4S coupe||84,165||3240||25.98|
|Ohio-class Trident submarine||1,900,000,000||33,528,000||56.67|
|F-15C Eagle fighter||34,300,000||44,630||768.54|
|basic formula one car||2,000,000||1320||1515.15|
Sources: The car figures were lifted from Intel liChoice.com or from our files, and suggested prices include destination charge and gas-guzzler tax. Other consumer products were rigorously researched at (my) local retail outlets. The info on military stuff is dead accurate, 'cause I found it on the Web. The price of the F1 car is admittedly only ballpark, as you can't buy one, period.-KS.