According to https://en.wikipedia.org/wiki/New_Tube_for_London https://en.wikipedia.org/wiki/New_Tube_for_London, "energy consumption 20 per cent lower than exi

According to https://en.wikipedia.org/wiki/New_Tube_for_London https://en.wikipedia.org/wiki/New_Tube_for_London, "energy consumption 20 per cent lower than existing trains due to regenerative brakes, LED lighting and lighter construction" ...and apparently they managed the "lighter construction" mostly by reducing the number of bogies? According to https://en.wikipedia.org/wiki/London_Underground_1973_Stock https://en.wikipedia.org/wiki/London_Underground_1973_Stock, current Piccadilly line trains have two 3-car units, which means 2x3x2 = 12 bogies. If you look at the video, the new train seems to be just one unit with 5 "actual" cars (with bogies) and 4 bogie-less segments suspended in between, which means just 10 bogies. Also, the new trains are 7 meters longer than the old ones.