The aptitude was not very hard, but time taking and manage your time wisely according to the topics you're pro in. Regarding the technical round, it mainly covered topics under design, manufacturing, and fluid mechanics and little metallurgy.
Don't try to be over-smart before the interviewer, being smart is good quality but maintaining overconfidence may fetch you many problems.
Try to express yourself to the interviewer rather than nodding 'yes' to anything he'd propose.