30 July 2001: Two brand-new powerplants for the new BMW 7-series have succeeded both in increasing power output and fuel economy, each by approximately 14%. They have also seriously extended service intervals, with oil-change intervals at up to 25,000 miles.

The engines are both V8 units, of 3.6- and 4.4-litre capacity, outputting 238bhp and 286bhp respectively. The key to the improved performance lies in the application of the most advanced engine management systems, including 'throttle-free load management' where the accelerator pedal acts directly on the Valvetronic system instead of a throttle butterfly.

The Valvetronic system enables an infinite adjustment of intake valve lift, and BMW has patented it, claiming it a 'quantum leap' in technology comparable to the transition from the carburettor to fuel injection.

"The level of fuel economy achieved in this way is comparable to the kind only diesel engines were able to provide just a few years ago," a BMW engineer says. "At the same time, Valvetronic offers at least the same reduction in fuel consumption as a modern direct-injection petrol engine, but without compromises in terms of emissions."

Valvetronic also makes for a smoother throttle action, and quicker reaction to the accelerator because the engine load management is taking place directly at the combustion chamber, instead of the intake manifold.

A fully variable intake manifold system also used in the new engines is the first of its kind in the world, while another technology patented by BMW adjusts infinitely the beginning and end of the intake and outlet camshaft opening process from 'advance' to 'retard' and vice versa. This bi-VANOS system provides more torque at low and medium engine speeds, means improved idling qualities and pollution at idling because there are less unburnt residual gases at idle, leads to lower fuel consumption and less exterior engine noise.

Other features in these 'ground-up' redesigned engines include lighter engineering designs, , a shorter stroke than previously, and cylinder head components with designed-in less friction.

The longer oil-change intervals are possible because of the provision of sensors which indicate the current condition of the oil as well as the more usual temperature and levels of the lubricant, and the information of how many miles can be travelled before the next oil change is constantly updated by the engine management system, depending on how the lubricant is standing up to varying driving conditions. BB