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Is the new 3.6 motor more economical than the older 3.8 and does it still do around 1800rpm at 100kph.
In general, a new engine will always have better or at least equal fuel consumption to the one it replaces.
The benefits can be more focused on engine performance/torque as well as a reduction in tail pipe emissions.
I’m not sure the fuel consumption in this case would be horrendously better.
No idea on the rpm/speed. You would have to think 1800rpm/100kph would be close.