Mercedes V6 comes clean on environment

By Russell Williamson

MERCEDES-BENZ customers can rest easy with the knowledge that Mercedes is developing cleaner, lighter and more economical engines.

Mercedes claims its range of V6 engines, which power the C- Class and E-Class range initially, using dual-ignition technology, has produced an engine whose emissions are 50 percent below present European Union values and United States regulations for low-emission vehicles.

The new V6 engine range will be an all-alloy construction, that Mercedes claims is among the most environmentally compatible six-cylinder unit in the world.

The German carmaker promises the biggest capacity unit in the range, the 3.2-liter power plant, will offer a 40 percent reduction in emissions, 13 percent increase in fuel efficiency and more torque at lower engine revs than the superseded straight six.

Many of these benefits can be traced to a significant weight reduction of 50kg or 25 percent compared to the previous in-line six-cylinder engine.

But replacing the iron block of the in-line six with an alloy unit, and using more lightweight metals such as magnesium for the intake pipe and cylinder head cover, has been just part of the means of achieving environmental and efficiency gains.

By removing one exhaust valve per cylinder, Mercedes engineers have been able to reduce the heat loss from the exhaust gas flow by about 70 degrees compared with the four-valve engine.

This, in turn, enables the catalytic converter to reach its optimum temperature for reducing emissions 12 seconds earlier.

By having the catalytic converter operating more efficiently sooner, the level of emissions from cold starts is significantly reduced.

A further reduction of emissions is achieved by using two spark plugs in each cylinder, enabling the engine to burn the fuel at almost 100 percent efficiency.

But the environment is not the only benefactor of Mercedes' new V6 power plants because the engines also promise greater drivability.

Although the maximum power and torque figures for the 3.2- liter V6 -- 165kW at 5600rpm and 315Nm at 3000rpm -- are similar to the in-line six, more torque is available much lower down in the rev band.

The peak torque comes in 850rpm lower than in the straight six with the V6 offering more than 95 percent of available torque from as low as 2500rpm.

In addition to the new engine, the V6 E320 will benefit from an upgrade that includes a host of new technology.

To improve security, the E320 will use an electronic starter switch that automatically verifies the electronic code in the key before starting the engine.

To improve safety, an advanced traction control system and Brake Assist emergency stopping aid will be fitted as standard.

The Mercedes E320 will also debut the company's needs-based service indicator system that can extend the scheduled service intervals from 15,000km to as much 22,500km.