Do you have to sell the wagon? Why not keep it? If you decide to sell, my guess is, you will miss it for about five minutes.
The 300E is smoother, quieter, more comfortable and quicker. You will miss however, the fuel mileage. You'll get 18-20 MPG with the 300E
The only possible draw back is, you may have to face the repairs you have already made to the 300TD. My guess is, you won't mind because you'll e enjoying the "new" car so much.
91 300E 120K
90 300SE 275K (sold)
92 BMW 525iM 120K
90 BMW 525iA 175K
85 300D 175K (sold)
84 300SD 245K (sold)