Simonsen's lap last weekend was a staggering 2:04.9560.
The car's almost unbelievable time makes it a firm favourite for the Armor All 12-hour endurance race at Bathurst in February.
Maranello Motorsport managing director Mark Coffey is impressed with the speed that the Ferrari has shown straight away.
"The 458 is a great car. It's worth the wait and really is amazing how the time we spent at the factory with Michelotto has paid off with the car so quick and stable so quickly," he said. "It's terrific to not need months to dial it in ... to now have confirmation of the new record during the team's first test is very exciting ..."
The 458 Italia in road form is an awesome piece of go-fast machinery, as is its drop-top stablemate. But the race version out of Ferrari's Corse Clienti department is nothing short of mind-blowing, making 410kW at 8500rpm, while fitted with the dual 55.5mm restrictors demanded by the FIA's GT3 rulebook.
Its 4498cc aluminium V8 makes 530Nm - more than enough to push the 1215kg machine along. Everything is composite except the aluminium roof and bonnet, with glass replaced by Lexan for the side and rear windows. Being a Ferrari factory race car, there's no shortage of tech toys to help teams milk the best results possible. The 458 GT3 packs a Bosch MED9 engine management system, with adjustable traction control and live-adjustable mapping.
A data-acquisition system includes sensors for suspension dampers, steering wheel angle, brake pressure, clutch pressure, cockpit temperature - and also packs an X/Y axis accelerometer and gyroscope.
There are even two exhaust options, depending on the whinge factor of those around the tracks - the non-silenced exhaust that comes fitted to the car as standard allows it to sing its wonderful tune at a rowdy 114dB, but a silenced version will cut it down to a slightly deafening 108dB.
"This car is damn fast!" said Simonsen, who will contest the 12-hour with Maranello offsider Peter Edwards.
"Given this is our first test, it's certainly nice to break the lap record finally and we did it in style.
"From the first laps at Bathurst the car was very quick, given it has a great setup baseline from running in Europe this year so we knew we'd be able to work from where they'd left off."
