Hello,
Car designs reset at the end of every season.
One of the reasons your new design is abnormally low, is your CD - always try to have a CD which is 5* (or the same level as your team) with a strength in one of the big 4 - This will help to maximise your start of season design.
More information, including what is defined as "Big 4" and how start of season design is calculated, can be found in the Car Design guide, written by SuperMod, Kevin Bissell.
The guide can be found
here.
I hope this helps, but if you have any further questions, feel free to ask.
