Lotus rewrites the rules on small sports cars and engine design
by Christopher A. Sawyer
In Hethel, home of Group Lotus, change is a constant. As are tight budgets and turmoil. Fresh off its purchase by Bugatti International, which also owns superior maker Bugatti Automobili, Lotus charted a new course. With the proceeds from the sale of the Elan and its assembly line to Kia in Korea, it developed the Elise, a car fresh in it construction method, materials, and execution. And one that would seek to re-establish the Lotus look, sprit, and style. In addition, it dug deep into its reserves and bankrolled a diminutive twin turbo V8, the fist new Lotus engine in over 20 years. If this wasnít enough, the company set a tight timeline for the projects. Both M111, the Elise, and Project 618, the V8, would spring from a clean sheet to production in just over 24 months.
Beneath the bodywork sits the heart of the Elise, an extruded aluminum spaceframe of stunning simplicity and sophistication. Except for the door beams and rear subframe, there are no welds, only structural bonds and a few mechanical fasteners in peel-prone areas. It as been designed-protected for all present and proposed safety standards, is made from 27 different extrusions, and weight just 65 kg. (143 lbs.) bare.
A pair of lateral torque cells joined by longitudinal beams make up the Elise frame. The front unit carries the suspension pickups, provides space for the battery and reservoirs, and ties into the instrument panel beam. The latter is designed for either right- or left-hand drive, acts as the knee bolster, and is an interior trim surface. In Lotus tradition, one piece does more than one job. "If you try to design with extrusions in a conventional manner," says Richard Rackham, senior design engineer-vehicle engineering, "you don't save much weight, and the structure isn't very rigid or dimensionally stable. And the cost of an extrusion die is the same no matter how many features you put on it, so you can put details in for free."
The rear torque cell separates the passenger and engine compartments, and contains a centrally located, 10.6 gallon fuel tank. This protects against increases rear crash standards, and reduces the fuel load's effect on handling. Extrusions are not used in the rear subframe because they would need steel reinforcements, not meet hard-point requirements, and-with a heat conductivity four times that of steel-might not stay glued together. Instead, a spot-welded, hot-dip galvanized design simulates an extruded section.
Each extruded member is tied to its neighbor by a tongue-in-groove joint. The joints are adhesively bonded (each section has ridges that control bond thickness), with critical areas gaining Torxhead fasteners to prevent them from peeling apart in severe accidents.
Up front, the aluminum radiator sits atop a composite structure that contains the intake plenum and brake ducts. But its duty extends far beyond these simple tasks. By adjusting the taper and length of its internal beams, Lotus engineers have designed it to manage the crash event. In the Elise's 30 mph barrier crash test, the unit performed as planned, leaving no more than a dimesized dent in the aluminum front structure. The car could have been driven away.
In European spec., the Elise weighs just 1485 Ibs. Prototypes are powered by Rover 120 hp. 1.8L, K-Series in-line 4-cylinder engines, though a 140 hp version is rumored. (The chassis can accept powerplants of up to 200 hp.) It mates to a 5-speed manual gearbox sourced from Rover's former partner, Honda, which means the Elise uses the same powertrain as the MG-F, but is nearly 900 Ibs. lighter. Lotus very conservatively estimates 0-60 mph times of "6.0 seconds or less.
The chassis design keeps suspension pick-up points well within the allotted 0.5 mm design tolerance. Droop travel is a generous 60 mm, while bump travel is an amazing 100 mmóalthough not all of that is used. For racing, the car can be lowered by 50 mm, which still gives a ground clearance of approximately 3 in. with two aboard, and leaves 50 mm of bump travel. Dual A-arms, coil springs and monotube dampers are used all around. A thin antiroll bar is used up front.
Chief designer Julian Thompson has been criticized for creating a car that is too "retry "busy," and "lumpy." Not surprisingly, he disagrees.
"Lotus hasn't had a very logical design and styling path over the past few years," says Thompson. "The Esprit (a Giugiaro shape updated by Peter Stevens) doesn't hearken back to any previous Lotus designs. So we were conscious that we had to develop a design philosophy in this car that could be conveyed to others in our line."
The Elise retains the mischievously smiling air intake, making it a prominent feature of the rounded nose section. And small, round headlamps are housed under clear plastic covers, while Europa-like indicator lights sit just forward of the twin radiator exits.
Thompson had wanted unique headlamps for the Elise, an extravagance the company could not afford, and settled for a single unique lamp. But, in true Lotus fashion, he made the single part do more than one job. The front indicators and four taillights are the same piece, mounted at different angles, and formed in different color plastic.
The body has a definite Coke-bottle section when viewed from above, which accentuates the position of the wheels. Their 5-spoke design gives an almost unobstructed view of the 11.2-in. aluminum metal matrix brakes, which can haul the Elise down at the rate of 1.2 g. Small intakes reside behind either door, whileójust above the cabin tapers gently back to a pair of flying buttresses capped an exposed roll bar anodized to match the rest of the aluminum structure. A rear spoiler offsets any lift (a downforce-producing undertray can be ordered), while chin tabs keep the nose on the ground.
Clambering aboard takes a bit of dexterity, requiring a step over the tall side sill and onto the cross-car beam directly ahead of the seats. Top up, it could be a difficult proposition. The driver's seat is set slightly closer to the vehicle centerline than the passenger's, which is fixed in its rearmost position. The view from the driver's seat is quite good, and full of interesting cues. In dark colors, the anodized aluminum spaceframe is a stark, purposeful contrast reminiscent of old sports racers. This image is helped by the rising fender peaks, sparse instrumentation and form-fitting seats.
With just 1485 Ibs. to motivate, the raspy Rover engine gets the Elise up to speed with an unaccustomed ease. Zero-to-60 times of less than the estimated six seconds should be easily attainable.
The gear linkage, also sourced from the MG-F, shifts precisely, and is topped by a large aluminum ball. Heel-and-toe downshifts come easily, helped by the location and rigidity of the extruded aluminum pedals. Prototypes were not fitted with the extruded dead pedal, whose design will also be used to provide a pair of footrests for the passenger.
As expected, the lightweight Elise changes direction quickly almost instantaneously, with little or no nervousness. Like its Esprit brother, it can be balanced on the throttle, or made to oversteer when given enough stick. Response is progressive, as is the ride.
Accelerating hard out of Windsock Bend along the long main straight at l Lotusí Hethel test track, the Elise takes on a racer's stance. Low to the ground, it rapidly eats the distance to the chicane. A quick stab at the pedal sheds momentum instantly a momentary chirp from the right front just audible above the tickle of air coming back around the roll bar. Thankfully, the heater is more than powerful enough to keep driver and passenger warm on a clammy, 50° English day.
Even in its present state, the Elise would be a welcome addition to the U.S. market. It speaks to the buyer in search of simple pleasures, efficient speed and true road racer breeding. But that buyer will have to wait until Lotus can devise a way to federalize the car. A new powertrain is needed to meet U.S. emission standards, crash testing must be conducted, and airbags fitted. These items alone could cost the company as much as it took to design and develop the car. Should another company decide to accept Lotus's offer to use the Elise chassis for its own sports car, however, these problems could fade quickly. If not, U.S. enthusiasts will just have to wait until this carnival ride comes to town.
22 BRITISH CAR APRIL-MAY 1996