Fuel tank capacity is listed under "Capacities". Porsche does not recommend the use of fuel additives.
Fuel is highly flammable and harmful to health.
If you lose the tank cap, you must replace it only with an original part to reduce the possibility of a fire in the event of a collision.
Your engine is designed to provide optimum performance and fuel economy using unleaded premium fuel with an octane rating of 98 RON (93 CLC or AKI). Porsche therefore recommends the use of these fuels in your vehicle.
Porsche also recognizes that these fuels may not always be available. Be assured that your vehicle will operate properly on unleaded premium fuels with octane numbers of at least 95 RON (90 CLC or AKI), since the engine's "Electronic Oktane™ knock control" will adapt the ignition timing, if necessary.
It is important to observe the regular service intervals, and particularly the oil change intervals, specified in the "Maintenance" booklet.
The use of UNLEADED FUEL ONLY is critically important to the life of the catalytic converters. Deposits from leaded fuels will ruin the converters and make it ineffective as an emission control device.
Cars with catalytic converters have a smaller fuel tank opening, and gas station pumps have smaller nozzles. This will prevent accidental pumping of leaded fuel into cars with catalytic converters.