Kevin Doyle scored his first away goal and the side who were in the Premier League last term broke off their celebrations for Noel Hunt to knock in the second from ten yards.
Always that much faster on the ball Reading threatened to over-run a Bristol City side who had decided to rest their targetman Dele Adebola.
It left them with no-one to win the ball in the air or hold up play. With the visitors centre back Andre Bikey ruling his penalty area, City's new front pairing of Stern John and Nicky Maynard struggled.
John, on loan from Southampton and starting for the first time, eventually made an opening for a shot outside the far post which was countered by a superb save.
Marcus Hahnemann somehow fished that one out of from the angle behind his right shoulder and when John finally got a shot past him in added-on time, the game had long passed City by.
Playing with three men up Reading simply overpowered a side badly missing the experience in defence of injured captain Louis Carey.
Any thoughts of a home revival after manager Gary Johnson's half-time team talk were quickly snuffed out inside ten minutes.
Doyle was put in to grab his second goal taking his total so far to 11 and Kalifa Cisse put in a solo run for the fourth as City failed to challenge.
It was a signal for the home side to send on their three subs with orders to stir things up by hard running.
Reading easily saw off that threat until John was played onside by Liam Rosenior for his late strike, but had earlier responded to City's use of their subs by withdrawing strikers Doyle and Noel Hunt - their job done.