I kid you not!
MB, to be all official about it, says DO NOT insert a suction probe into the dipstick tube. I'm not knocking others doing so, especially in their own driveways. The MB way, and the fastest way, which is important when you're on flat-rate, is to use the dipstick tube adapter. It has 2 o-rings on it and seals to the wide top part of the dipstick tube, using the entire tube essentially as a probe into the crankcase. The bottom of the tube is within fractions of an inch of the bottom of the oil pan on MOST MB engines produced in the last 10 or 15 years or so. I believe they have done oil changes like this in Europe for quite some time now.
As a test (I didn't trust it at first either, and flat-rate or not, I'm picky) I did an evacuation procedure on several MB engines and then checked the amount of oil left. On anything you'll find now, except the 111 engine, NO oil will come out, it's that close to the pan bottom. The 111 motor I think the dipstick tube isn't that close. By evacuating using the tube as a probe, I only get a quart or 2 out, so I am "forced" to either use a probe, which does come with our equipment, or I pull the drainplug. As Blackmercedes (John?) says, it works OK with the probe, just takes longer, and you can go ahead and check tire pressures or something (coffee break?) while the sucker do it's thang.
On more vintage engines, it works good back into the 80's, say on 617 Diesels, 102 and 103 engines. Doesn't seem to work the best on 116/117 engines, I pull the plug on those. On the 107 chassis, us lazy MB techs usually want to raise those up in the air to do the oil filter anyways, they all go up from the bottom on 107's, so I usually pull the plug on 107's, plus it's soooo much fun pulling the big oil drain plug on a 107 anyways!
The oil sucker we have is air operated, not a displacement pump, though. Seems to be venturi operated, creates a vacuum in this glass cylinder that holds a couple gallons, the cylinder it mounted on top of a holding tank, which holds around 40 gallons, I estimate, good for about 5-6 112 or 113 engine oil changes.