Are fuel separation systems like Fass Fuel System a must install in diesel vehicles like my 2008 Mercedes-Benz M-Class ML 320 CDI? Will it do anything to improve my vehicle's performane?

any water separator is a good thing,however make sure enough fuel pressure

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Fuel Air Separation System

Your fuel system is pressurized from the tank to the injectors. No suction, no air infiltration, no need.

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Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO

Not a scam as it includes a water separator. Beyond that I really have my doubts.

Low price to get you in the door but then you have to buy their replacement fuel filter.

The way of the human condition. If you expect to see improvement you can imagine it. I can think of no way this can increase fuel milage unless your old filter is obstructed. I base this on many people claiming a 1-2 mile improvement just by changing out an old fuel filter.

A Cat 1R-0750 (or equivalent large,r finer filter) would be the only worthwhile filter mod IMO, and that's nothing to do with performance, only change intervals and better filtration.

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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

These ain't Dodge Cummins with their horribly under sized and poorly designed fuel systems feeding a $1,000 VP44 before the problems with the VP were fixed.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.