The most energy-efficient tractor types on the market today are: – The John Deere 9400/9420 24 Speed 312 HP, – AGCO Challenger MT 845 Track 338 HP, – Case IH STX 325/New Holland TJ 325 292 HP, and – Massey Ferguson 8600 Series. These machines have been tested by the Nebraska Tractor Test Laboratory and have achieved an impressive 18.15 hp-hr/gal, 18.14 hp-hr/gal, 18.13 hp-hr/gal, and 16.6 hp-hr/gal respectively.