Someone will be able to post all the relevant info and screen shots etc, but just to get started

The car handles as good as some fully upped cars with no upgrades
Takes 4 hrs to upgrade
Day 1 and tier 4 needs level 1 upgrades done

as an aside, tier 3 event needs 225 kms per hr hit 4 times. I initially thought it was 1 lap requirement and struggled to hit it 4 times with no upgrades, but as I passed the finish line after lap 1, I realised the event is for 2 laps and a breeze :)