I rented a 182Q model for a trip to oshkosh and we flight planned 125kts. Only complaint was the fbo begged you to run 75 deg ROP because renters were over leaning and destroying the cylinders, which resulted in 14-15 gal/hr fuel burn.
Climb. Seriously. We have to run ROP in ours, and have a draggy STOL kit and we have averaged 11.5 over four years of fuel burn, but all of our flying is done at 8,000 MSL or higher due to the airport being at 6,000.
If you're flying a 182 around at full rental power down low, it's going to go about 5 knots faster and burn 2-4 more gallons an hour in fuel. Not worth it.
Climb up to where the engine isn't producing full power and re-lean as appropriate. Even with the loss in engine power at higher altitudes, once in cruise, the difference in True airspeed is enough that I flight plan 130 knots true in ours and it comes out "damn close". At max gross it'll be 125, especially if you can't load it as far aft as you'd like.
(If smooth in cruise, slide your seat all the way back to the lawyer-induced seat text stop, and you'll have to trip nose-down about three "bumps" on the trim wheel. Plus it's a fun trim exercise when you want to see how accurately you can trim it, since the wheel is hard to reach from there, and if you lean forward to re-trim you can see the pitch change on the altimeter. Heh. So far my best is 30 minutes without touching the trim wheel. If you get it right on, you can fly a 50' block just by shifting you weight fore and aft. LOL! The stuff you do to entertain yourself on a long long long XC in smooth air...)
I do NOT flight plan 130 for the climb, though, the 182, especially heavily loaded is a dog speed-wise in a climb. You'll see 90-100, depending on how shallow you can make the climb, when coming home from a lower elevation location. Climbs well, but it's slow.
This is why I miss time to climb speeds from some now-forever-unmentionable in flight chart software that I wouldn't ever use ever again because of the unmentionable things they did to push patent law to the limits of civilized behavior.
Foreflight has never bothered to do in their planning module, and it's long long long overdue. There's a profile view now, but the planner has no concept of different speeds in that profile, so I have no idea what the point of adding it was. Terrain, I guess. Doesn't show weather layers from the enroute METARs over the profile like the unmentionable software did either. Foreflight now almost a decade behind on that feature.
I don't bother pulling much if any power off in the descent, unless turbulence dictates, but that's only s few minutes at the higher speed and doesn't make that much of a difference on a long flight. It isn't a Mooney... You can pull the throttle back slowly a few mikes from the airport and it'll slow up to a wallowing lumbering 90 knot Cessna in the blink of an eye.
If you really want 140, go find a Mooney M20C that's been well cared for and forget hauling large loads. Trade-offs...