Since the tach appears to go above 6000, it's a safe bet it isn't the 2.0 TDI.
The user name had me wondering if it was the W (double V, not double U) four-motion 8 cylinder, but that one was automatic only so that's out of the possibilities.
That leaves the V6 (which if getting 38+ highway is already 'hypermiling'), and the 2.0.
2.0t is the 2 liter turbo gas engine. "four-motion" is their AWD system and is not part of specifying the engine. AFAIK, they are pronouncing W8 as "double U eight", I think in direct reference to its resemblence of the letter W rather than two U's.
In addition to the V6 and the 2.0t they have a 2.5L 5-cylinder, which is what's in my car, but it may not be available in the Passat. I know the 2.0t is.
Okay, just checked vw.com and for the current model year they only offer the 2.0t and the V6. No W8 this year? Seemed like a cool idea for an engine...
2005 and later (hard to tell which year with the aftermarket grille and no taillights visible in the image) had a 2.0t and also a 2.0 TDI. If its a 98~04 then it is quite likely gasoline powered as only three 98 TDI Passats were imported.
BTW, there is as yet no photographic evidence of these three 1998 1.9liter B5 TDI, but they are acknowledged by VWoA and a TDI only used car dealer has seen one of them in person at an auction.
The english markets call the W design as english speakers do: "Double U". The engine designers described it as resembling their letter which translates from German into "Double V". It's the local version of "double V" almost everywhere else. The letter looks the same, but the name changes with the language.
The W ("double you" in english, "dou-bleh vay" in french, "dopple vay" in german) 8 option was dropped when the Phaeton was canned.
What's the name of the letter Z: "zee" or "zed"?