Gas turbine
Gas turbine (turboshaft) engines offer a very high power-to-weight ratio and were starting to find favour in the late 20th century – however, they offer very poor fuel consumption and as such some armies are switching from gas turbines back to diesel engines (i.e. the Russian T-80 used a gas turbine engine, whereas the later T-90 does not). The US M1 Abrams is a notable example of a gas turbine powered tank.