Lamborghini’s Aventador LP 700-4 is doing something that supercars aren't exactly famous for – it’s saving fuel. Not satisfied with a car that can do 0 to 100 km/h (0-62 mph) in 2.9 seconds and hit a top speed of 350 km/h (217 mph), Lamborghini has fitted the Aventador LP 700-4 with a fuel economy system that includes an automatic engine start/stop and a cylinder deactivation system.

The Aventador caused quite a stir when it was launched last year at the Geneva Motor Show as the replacement for the venerable Murcielago. It was more than just a tweak here and there, with a new name. The Aventador was redesigned and reengineered from the ground up and then, in a classic example of trend bucking, Lamborghini dropped in a 6.5-liter V12 engine putting out an eye-watering 700 HP (515 kW). Now the company is tinkering with the Aventador LP 700-4 by adding in some fuel-saving innovations.

The start/stop engine system isn’t that new, though it’s generally something associated more with MINI Coopers and Honda Civics. In a supercar, it is a bit unusual to fit a system that shuts the engine off when you stop at a light, but Lamborghini has added a twist. In the LP 700-4, the start/stop responds in 180 milliseconds, which means that when you hit the accelerator, the full power of the V12 is online faster than a gnat’s sneeze.

Lamborghini’s rationale for doing this goes beyond saving a bit of petrol while waiting for the light to turn green. By using the start/stop, the LP 700-4 can use supercapacitors instead of batteries to kick the engine. This not only allows for extremely fast restarts, but it also saves three kilograms (6.61 lb) of vehicle weight because the batteries only need to run the electronics. As a bonus, this puts less strain on the battery and makes it possible for it to last the life of the car.

The other new feature is the Cylinder Deactivation System (CDS). The problem with a V12 is that while it may be great at the track, in town driving it can be a bone-rattling experience as you try to keep 700 horses on a lead. It also eats up fuel. With the CDS, the LP 700-4 responds to traveling at speeds of less than 135 km/h (84 mph) by shutting down one cylinder bank – turning the V12 into a V6. Pressing the accelerator switches all twelve cylinders back on.

The third fuel-saving tweak by Lamborghini is that the LP 700-4 makes greater use of composites. Along with its carbon fiber monocoque body, Lamborghini is also offering an optional carbon fiber package of front spoiler, air intakes, engine cover and other components. Since the Aventador was the Lambo that was meant to make a priority of handling over speed, the designers took advantage of the weight savings by adding stiffer springs and optimized dampers.

The result of all this is that the Aventador LP 700-4 saves fuel by a factor of seven percent or 16 liters per 100 km (14.7 mpg). The only question is, why? The technology is very impressive, but fuel economy in a supercar is truly penny wise and pound foolish. With a price tag of US$379,700, offering a seven percent fuel savings is a bit like buying the Hope Diamond and getting a coupon for a free latte with it.

As to protecting the environment, there will only be a few thousand Aventadors built and they’ll spend most of their lives in storage or being hauled every few weeks on flatbeds to the track and back into storage. If Lamborghini wanted to save the planet, it would be better off redesigning the truck engine.

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