The new color displays use bonded LED and LCD displays, which allow them to get better visibility with less power. In addition, they use color to allow better night vision at lower power settings. But the real kicker is that they are multi-function devices, so one of them can take the place of 3-4 old single-function displays. Not to mention that things like old wind instruments, which mechanically turned an indicator needle were power hogs.
Take our Triton displays compared to our old B&G network displays, for instance. A single Triton has more functionality than all three of our old Networks. At full light power, the Triton uses 155mA while the Network displays used 100mA. So three of the Network were less efficient than a single Triton, and together provided a lot less data than the single Triton. However, at night lighting levels, the Triton display draws 45mA, while the Networks drew 100mA each.
This is for the color display example. Similar B/W LCD displays (the Simrad IS20, for example) use much less power while still providing more data. In the case of the IS20, it uses 0.11mA, which is lower than any old instrument managed.
Mark