^Ask how many students actually make the transition from CMC to the engineering school in the 3/2 program. I have heard (mostly here) that at many LACs students don’t actually transfer out. I think this probably varies from school to school - some schools may have a better track record than others. Chat with the director of that program and ask how many people transfer and why people change their minds when they don’t.
Usually with a 3/2 program, it’s not competitive - if you have certain credentials, you are guaranteed admission. That’s usually not the case with university engineering programs if you aren’t admitted as a freshman. So I would weigh that, and weigh what else you would major in at UCSD in the even that you don’t get into engineering. (Also, if you want to do engineering, why would you major in economics?)