I am looking at a 2000 sentra to replace the 1999 sentra that got T-Boned
last year.

Here is the car I want to get:

2000 Dark Red Sentra XE 49K miles, Manual Transmission, good shape,  from a
local Nissan Dealer.
The asking price is 7400 + roughly 700 used car fee + TTL.

I was thinking about doing this offering my 1999 car (the passenger doors
will NOT open and the doors are pretty much smashed, otherwise everything
else in the car works perfectly, still gets 35-40 MPH) and offering $4500 on
top of that

Is that too little?  What should I offer in your opinion?

Thanks so much

John