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I'm interested in learning details of how the MDS works. "rexrcr" has a post over on "Post your fuel mileage estimates here" describing some automatic control features that I was unaware of. He seems to be our most knowledgeable member in this area. Anyone else have some knowledge to share?

I have read that MDS is not the same (mechanically, at least) as the cylinder deactivation used in MB engines. Thoughts on this anyone?

I estimate that MDS might save $1,500 dollars or so in fuel over the life of the vehicle at today's prices (not a whole lot, in the big picture). It costs something to build it into the engine and probably something to maintain it a few years down the road. Is it one of those things that really isn't going to pay off financially? Environmentally could be a whole other issue. Comments?
 

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Chrysler announced some new technology for their Hemi engines in the 2005 Chrysler 300C and Dodge Magnum RT. They call it a Multi-Displacement System (MDS) and it deactivates cylinders on the engine when they are not needed. MDS converts the powerful Hemi 8-cylinder engine into a high fuel economy four cylinder engine or back again and it does it in just 40 milliseconds. By switching from 8 cylinders to 4 cylinder operation when the power is not needed, fuel economy is improved by up to 20 percent. Average fuel economy gains will likely be closer to about 10 percent. Step on the throttle and the engine instantly switches on all the cylinders for full power.

Two technological features enable this to happen. The first is Electronic Throttle Control. The computer changes the throttle opening at the same time it switches cylinder operation. Drivers will not notice any surges or change in the feel of the engine. There is just power when needed.

The second feature is valve lifters that can be deactivated. When the computer deactivates the lifters, the valves stop opening. Energy is not lost by pumping air through these cylinders. Combustion is stopped and fuel to those cylinders is turned off. "The MDS was part of the engine's original design," said Bob Lee, Vice President Powertrain Product Team, Chrysler Group. The Hemi engine with MDS has completed over 6.5 million customer-equivalent miles of testing in Chrysler's development centres and is covered by their 7-Year/70,000 mi Limited Powertrain warranty. :D
 
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