cruise speeds

Anyone have good info on real-world planning KTAS speeds for Cessna 182 and Mooney M20E? Lots of other differences in the two aircraft, but I'm trying to determine cruise speeds. For example, an 856nm flight - KBJC KSAF KABQ KALM KBJC - gives me the following times for 865nm: 120 kts 7:13 125...