We used to joke when taxiing out that we had all 5 APU's running! At idle, each engine burned the same fuel as the APU (300 pph). The LF-507's are flat rated to 7000 lbs of thrust. The engine in and of itself is not a terrible fuel consumer, but when you put four of them together and hang them on an airframe that is as "draggy" as the RJ85, you get some pretty high numbers. For example here are the down and dirty rules of thumb.

In the terminal area (approach vectoring etc.) plan on 100 lbs per MINUTE.
First hour of flight (takeoff climb and initial cruise) = 6000 lbs.
Subsequent hours = 5000 lbs/hr.

With 20,640 total lbs. onboard, she was a 4 hour airplane.

Here are some real world numbers:
OKC-MSP at FL300: Burnoff = 7930 lbs (1:33 flight time) = 5116 pph
DTW-PWM at FL310: Burnoff = 7211 lbs (1:26 flight time) = 5031 pph
DSM-DCA at FL310: Burnoff = 8841 lbs (1:50 flight time) = 4822 pph
EWR-MEM at FL300: Burnoff = 12217 lbs (2:24 flight Time) = 5090 pph
DFW-MSP at FL310: Burnoff = 11021 ;bs (2:05 flight time) = 5290 pph

All averages out to about 5070 pph cruising. I have never flown the CRJ or EMB-170, But I have to imagine that their cruise burn is somewhere in the 4000 pph range give or take.

Basically when you look at numbers, the RJ85 burns roughly the same as an A319/320, goes 30 knots slower at cruise and carries half the people. The economics with only 69 seats on the jet didn't make sense.

It is QUITE comfortable up front lots of width made you feel like you were in a lot bigger airplane. Digital autopilot, autothrottles and AUTOLAND made her a sweet machine for those "long" legs. Full size flight case fits with room to spare for laptop and cooler beside you, seats go way back for lots of leg strech room (at least at my 5'9" stature). Nice wide center console made for lots of storage for reading material, suduko puzzles and sorting through the Jepp updates. GOD I am going to miss that!