I've heard nightmare stories gas buying and prices. Are they true?
No, the gas pumps don't eat human flesh, but they will drain your credit card. The first issue, however, is finding gas stations that are open (and knowing where they are, at least in urban centers).
Some perspective: Italian cities and towns are often cramped and naturally ancient. The North American "mall" island doesn't exist, except in highway rest-stops. That leaves you with often tiny strips off on major strips or on piazzas, often with cars parked all around. Full-service is rare. More often you'll find automated pumps that allow you to slip in €5, €10, and €20 euro bills. Wise to keep some "ironed" if your on a trip. Crumpled bills annoy the system and can lead to anxiety. Some automated pumps take plastic, but not all. Don't hit the road without some bills handy.
Aperto 24 means 24/7 until the pump runs out of gas, which can happen on long weekends.
Word to the wise, always fill up, and if you drop to half-a-tank, pull over and fill up when you find an open station. Don’t play the red-light waiting game at the risk of running dry. Don’t expect to find rural stations open at lunch hour, 2-4:30 p.m. — in fact, plenty of city stations also shut down at lunch. Not, repeat not, a smart idea to decide you want to gas up at 2 p.m. on a Sunday. Good luck, even in Rome.
Depending on the time of year and demand, gas sells at about €1.7-€1.9 per liter (diesel runs about €1.6), and a liter is a little more than a quarter of a gallon. The math isn’t pretty. Fifteen gallons is about 56 liters — about $110, about double most prices in the United States.
Don't go shopping for cheaper gas. Prices are mostly locked in. Also, if you’re in the sticks, make sure you're pumping unleaded (senza piombo), which is the EU passenger car norm, but things can occasionally get dicey.