Quickly shifting Gears gives throttle power

When quickly upshifting and down shifting in f125 time trials, I was able to gain speed going uphill even when I wasn't touching the throttle and the engine didn't sound like it was producing any power. I was in the Red Bull car with equal performance on when it happened but I have not tested it on any of the other cars. It didn't seem to require a specific set of gears to shifting between to get this affect but it did seem that very moderatly specific timing (which was very easy to replicate) was needed.