I think it is the price of current model year cars
For the first red, you don't need an article before "relationship".
When you're saying "type of [word]", do not put any article before that word.
Example: "a type of device"
Not too sure about the "your back" parts. It could be your teacher does not like repition.
Also not too sure about "did". He probably wanted you to use the word "felt" instead of "did feel"
The first word of the last paragraph should be "in" not "at".
The red commas definitely do not need to be there.
Don't know why he marked "time to" and "to" red.
