My son is in Year 13 and has applied for Mech Eng so I can tell you what he has/hasn’t done and what the outcome has been so far. His situation might give you a little bit of reassurance. The admissions process is a mystery to me as he isn’t a particularly strong candidate compared to many but has still managed to secure some good offers so has been very fortunate.
Like your son, Mech Eng has not been his life long passion. He just knew that he loves Maths and Physics and wanted to take them further without doing a pure Maths or Physics degree. He actually didn’t finalize his degree choice until just before Christmas when he applied.
His A-levels are Maths, Further Maths and Physics. Predicted A* A A. No EPQ. He got an offer from Southampton in February, followed by Loughborough then Birmingham in March. Bath responded a few weeks ago but have offered him Robotics. He is still waiting to hear from Bristol.
His PS was well written but it didn’t demonstrate a passion for Mech Eng specifically. It was more about his passion for Maths and Physics that has now led onto an interest in engineering etc. This is probably why Bath didn’t offer the ultra competitive Mech course. I feel that Bath and Bristol were always a long shot anyway as you’re competing against students that have a history of interest in Mech and probably 3/4 predicted A’s/A*’s, a relevant EPQ plus work experience.
I have been told that Bath do read the PS but I don’t know for sure. Although the e-mail they sent about the course switch did make it sound like they had. I have no idea about the other universities. Maybe Bath thought his passion for Maths/Physics was a good fit for Robotics. Who knows.
I hope that other people have given you some good ideas for boosting the PS. However, it is still possible to get offers with very little but it’s nerve wracking when you know you are up against some outstanding students. I would recommend something online in a relevant subject that he can do over the summer holidays? My son did something relating to physics. I’m sure school can advise on this. I’m guessing admissions first look at predicted grades and subjects, whether you are state, selective or private school then use the PS if necessary to make final decisions??
Good luck.