Their fourth successive triumph moved them three points clear of arch-rivals Coleg y Cymoedd at the top of the table with two games left to play in the regular season. They still have to travel to face Cowbridge CS and Gwent College.
Centre Joe Roberts scored two first-half tries for Sir Gar and there were other tries from wing Tom Rogers, skipper and lock Lewis Ellis-Jones and full back Harri Doel. Centre Scott Lloyd and outside half Llew Smith landed one conversion apiece.
To their credit, injury hit Cardiff & Vale were highly competitive in the first half and a try from prop Dylan Lawley, converted by outside half Tony Lamerton, made it 7-7 on the half-hour mark. After that, though, Sir Gar turned up the pressure and picked up the points.
Cowbridge’s game with Gower College at St Helen’s, Swansea, fell foul of the weather and the other game in the Cup competition ended up in an away win for Gwent College in Pembrokeshire, 20-10.
In the Trophy, Newport HS made it four out of four as they ended their run of home games with a thumping 38-18 win over Whitchurch HS. There were six tries from the home side, with centre Corey Howells crossing for one of them in a man of the match display.
Newport raced into a 21 point lead in as many minutes as they hit their visitors with a blistering burst. There were tries from outside half Lewis Hopkins, lock Calum Hague and tight head prop Josh Reynolds.
Full back Reagon Mahoney converted all three scores and added another one after Howells had raced over moments after Whitchurch skipper Sion Parry had finally got his side on the board with a try that Conor Nagle improved.
Whitchurch wing Kane Teear-Bourge grabbed a second try for the visitors and two Nagle penalties cut the gap to 10 points at 28-18. But Newport hit back with two late tries to wrap-up the victory, replacement scrum half Dan Babos and wing James McCarthy crossing.
Full back Tomi Lewis scored 10 points for Llandovery College as they beat Coleg Llandrillo 35-5 at Parc Eirias. Lewis joined No 8 Dylan Jones, skipper and hooker Ianto Jones, centre Ty Jones and back row man Rhodri Bullock among the try scorers and also kicked a conversion and penalty, with Aron Hemmings adding two more conversions.
CUP
Coleg Sir Gâr 29 7 Cardiff & Vale College
Gower College P P Cowbridge CS
Pembrokeshire College 10 20 Gwent College
TROPHY
Bridgend College 3 44 Ysgol Glantaf
Coleg Llandrillo 5 34 Llandovery College
Newport HS 38 18 Whitchurch HS