Currently a wide range of Russian military vehicles employ multifuel engines, such as the T-72 tank (multifuel diesel) and the T-80 (multifuel gas turbine).
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Perhaps the most notorious example from a military perspective is the L60 engine used by the British Chieftain Main Battle Tank, which resulted in a very sluggish performance -- in fact, the Mark I Chieftain (used only for training and similar activities) was so underpowered that some were incapable of mounting a tank transporter.