2003 VW Passat 1.8t what happens if I do not run Premium Fuel

the passats with the turbo engine needs the premium purely for the turbo. ive had mine for abt 2 months & found out the other day l needed it. it even says it on the gas cap. the turbo on any car needs the purest substance(premium shell v-power gas) plus oxygen to run smoothly. my mechanic told me that. if u dont run it on premium then u risk killin ur turbo, catalytic converter, engine, & basically everything else. ive had my check engine light on twice now, its in the shop right now actually. premium fuel on any car is the right choice, it makes the car run smoother. but u especially need premium extra super v-power gas on passats purely for the turbo. l hope this was of some help

It will run just fine.
However, when they gave the ''stats'' for the car eg. horsepower, 0 to 60 times & torque they were using premium. If u use less, u do not get the same performance. [Not that l time myself every time l take off(so if l am a sec or 2 slower l really do not notice or care)].
Turbo & fuel injection system & computer will run like normal.
l mean, what would u do, if all u had was lawnmower gas (or marine gas)? Leave the car in the driveway? Personally l would not. l am driving it.

The engine is ECU detects the use of non-premium fuel and retards the timing, which results in less power and torque. Your Owners Manual will be more specific.

your fine to not run premium. l own a 01 1.8t and i`ve only ran regular gas in it and it still pulls like a mother. you will get more advantages and pull with premium but so will your costs. its unnecessary. but if u can afford it, it wont hurt. if u dont.. no worries.