Tom Lance capped an excellent all-round performance to take 3-30, on top of his anchoring United's innings with 76 as opening batsman.
Only Tech opener Peter Czerwonka managed to hang in there, grinding his way to 41.
Conditions were not easy for batting as United had closed their innings just past the 200-mark, challenging if not all together imposing.
Lance survived a dropped catch to steer his team through, while Robbie Power provided an important cameo down the order, being unbeaten on about 30.
Tech medium pacer Josh Plumridge was the first bowler to complete a 15-over spell under the new rules for the Premier League, taking three wickets for 49.
The scorebooks recorded by the two teams with United innings did not quite match up at the close of play, so the version provided below is the compromised assessment.
In the other game, Saracens got their 2013 campaign off to a good start at home with a three-wicket win over Marist.
Their clubmates were not so fortunate in the Premier 2 Chairman's Cup final, as WHSOB cruised to a nine-wicket win.
Results
Porter Hire Premier 1: David Jones Motors United 203-7 (T Lance 76, R Power 30no, J Plumridge 3-49) bt St Johns Tech OB 103 (P Czerwonka 41, A Cording 5-21, T Lance 3-30). Silks Audit Marist 175 (G Singh 30, M Fraser 51, O Gordan 2-13) lost to Marton Saracens 177-7 (D Gordan 56, C Rayner 31no, B Turner 2-19).
Porter Hire Premier 2 - Chairmans Cup Final: Marton Saracens 92 (K Manuka 41, J George 3-14, J Tweed 2-0) lost to WHSOB 95-1 (J Sicely 51).