just got the car serviced today to get it ready for rego and i have a question ive been wanting to ask for a while.

everytime i get the car service, when i get it back it seems alot more responsive and when i give it the gas it accelerates alot better.
i had a look at the invoice and it seems like the work done was:
- visual inspection of undercarriage and exhaust
- lubes joints as necessary
- tire change (once in a while)
- engine oil change
- engine oil filter
- wheels removed, brakes rotated and checked

i notice that the handbrake is alot harder to pull. but besides all this im just curious to know which step is the actual one that makes the car more responsive? cause i change my own engine oil and filter/spark plugs/air filter.
only had to take it to shops to get the rego done, and when i change them i dont feel the responsiveness you get when you take it to the mechanics. do they do something that they dont put on the invoice purposly cause they dont want you to know????