Speed, and very little else. The 6170 prints up to 70 ppm A4, the 6160 up to 60 ppm and the 6155 up to 55 ppm; first-copy-out is approx. 2.7 seconds on the 6170 and approx. 2.9 seconds on the other two. Scanning is 270 ipm duplex on all three. Print resolution, paper handling, security, connectivity and the C-EXV 1002 toner are identical across the series, so the choice comes down to monthly volume and how much waiting at the device you can accept.

No — fax is an option, not a standard function. Standard functions are print, copy, scan, send and store. Super G3 fax requires the Super G3 FAX Board-AX2, a second line requires the Super G3 2nd Line Fax Board-BQ1, and IP fax requires the IP FAX Expansion Kit-B1@E. Tell us how you fax and we will quote the right board with the machine.

All three models use the Canon C-EXV 1002 BK black toner cartridge, rated at 65,500 pages estimated at 5% coverage. It is the only toner in the series, so consumable stock is the same whichever model you choose.

1,200 sheets as standard — two 550-sheet cassettes plus a 100-sheet multi-purpose tray. Adding the High Capacity Cassette Feeding Unit-F1 and the Paper Deck Unit-F2 takes it to 6,350 sheets. Output capacity reaches 3,450 sheets with the Staple Finisher-AB3 or Paper Folding/Booklet Finisher-A2 and the 3rd Copy Tray Kit-A1.