Having never owned a 240D, this my be an unfair assumption on my part. But, just about everyone I talk to with a 240D says the thing uses oil, especially at highway speeds.

My 83 300D used about a quart in 3000 miles.

I don't know what I did in my 52,000 miles of ownership with my 300SDL, but when I first got it, it used about a quart in 2000 miles, now it uses absolutely zero oil, I mean the oil is at the same exact spot on the dipstick as when I added it 3000 and somtimes 4000 miles before. Must be alot of wide open throttle