By allowing ads to appear on this site, you support the local businesses who, in turn, support great journalism.
Mercedes-Benz CLS63: Consumption optimizing
Placeholder Image

There is an eye in the hand-assembled engine of the 2012 Mercedes-Benz CLS63 AMG that gets it started on the right cylinder.

This re-engineered, high-performance sport sedan is equipped with a twin-turbocharged V-8 that has been technologically honed to death-ray precision and force. To help this mighty power plant save fuel and emissions, it has an auto-stop feature.

Common in gasoline-electric hybrid vehicles, auto-stop switches off the engine at traffic lights or other such situations and restarts instantly when the driver lifts a foot from the brake or steps on the accelerator.

This is a simple process in a hybrid vehicle, which has an alternate battery pack. The CLS63 relies on the starting power of the car’s “cranking” battery. To give it a boost, the engineers have added a crankshaft sensor that recognizes the direction of rotation and “sees” the resting position of all eight pistons.

For an instantaneous start, the cylinder with the most favorable piston position gets the injection of fuel into its combustion chamber. The precision of the piezoelectric injectors makes especially fast starts possible, Mercedes says.

To compensate the voltage drop during the restart, the CLS63 has a back-up-battery (12 amp-hours) in the trunk, which is connected to the vehicle power supply over a charge- and decoupling relay.

“If the battery voltage gets under a certain level, the engine will start — or if already running, it may not remain on — we refer to this as a stop preventer,” spokesman Rob Moran said. Other stop-preventers are fogged-up windows, an open hood or door, too much cooling requirement or insufficient vacuum in the brake booster, he said.

The hot-rodder’s maxim of “no replacement for displacement” is being challenged by modern muscle cars.

This second generation of the so-called “coupe sedan” gets a new 5.5-liter engine (replacing a larger V-8) that in standard trim is rated for 518 horsepower and 516 foot-pounds of torque from 1,750 to 5,000 rpm. Opt for the performance package, and the horsepower jumps to 550 with 590 foot-pounds of blacktop-plowing torque.

The car performs with agility and brutal launch force, including 0-60 mph in 4.4 seconds. And while these attributes are quite acceptable in this $100,000 class of luxury powerhouses, the CLS63 achieves non-guzzler fuel economy. And because it is sold around the world, it also has very low emissions for those standards in global markets.

Fuel economy ratings of 16 mpg city and 25 highway may sound challenged, but they are a prize-winning improvement over the previous model, which was rated 12/18 from a 507-hp, 6.3-liter biturbo V-8, which came with a $2,600 gas-guzzler tax.

As global standards for corporate average fuel economy and emissions get ever tougher to meet, many manufacturers are waving goodbye to the V-8. Mercedes-Benz has been able to meet the challenges, it says, by reduced displacement, direct injection, “smart” power management of accessories (such as steering and alternator), optimized transmissions, turbocharging and start-stop.

Technology is the minimizer for fuel and emissions — doing more with less for something enjoyable.