GRID 2

This has been flagged as missable since it is possible to complete the career and fail to achieve 5 Sponsor Objectives BUT highly unlikely

At the beginning of each new season of the Career in WSR you are given the option to pick some Objectives from various sponsors to try to beat, you are given 3 slots at first and are given more as you progress
Make sure to pick the easiest objectives that you think you can beat (such as reach a certain speed, drift certain feet, etc) as to make this trophy easy to unlock.

If you forget which objectives you have picked you can press whilst in your garage.

Completing 5 objectives is easy but be sure to pick 15 more easy ones to also work towards

This Achievement Requires You To complete 5 Career Sponsor Objectives. In The Beginning Of Each Club Race series And The WSR series of That season , You'll be prompted to select sponsors for yourself. Try To Select Easier Ones like:
"Win a Vehicle Challenge" , "Win A promo Event" , "Finish ahead of *** in *** Series" ,
"Win an Eliminator event" , ...
These Objectives can be completed until the end of that section and they can only be completed once. you can view your objectives by going to career and pressing X.