You need a hydrostatic regenerative brake.

http://www.boschrexroth.com/country_units/america/united_states/en/news_and_press/press_releases/brm/Rexroth_Hydrostatic_Regenerative_Brake/index.jsp

This company says it can be retrofitted to existing vehicles but I think they have trucks in mind.


Seriously though, diesel engines typically get their best fuel economy between the rpm their torque peaks at and their power peaks at. (what a great excuse to go get a dyno run ) This should help you figure out gearing.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

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