The phrase "extra ponies" typically refers to additional power or performance in a vehicle, similar to the way ponies (horses) give strength and speed. Full definition
In a typical midcycle refresh, its exterior style was tweaked some, and the GS 350's V - 6 picked up a couple of extra ponies, among other small changes. (automobilemag.com)
In terms of technical improvements, the new HPE600 package comes with a revised ECU unit, a sport exhaust system, new fuel injectors and a TVS2300 supercharger able to squeeze extra ponies from the 6.2 - liter V8 that equips the American beast. (automotorblog.com)
This is 27 extra ponies over the regular Turbo S, and while that torque figure is unchanged, the ES has 553 lb - ft on tap at all times — the pedestrian Turbo S only sees that peak briefly with the standard overboost function. (automobilemag.com)