"Earl had a few tests in the car and we get on really well. Earl also knows Timo really well from his time racing in his team [Team75 Motorsport GT outfit].
"I have to say we pushed really hard to get Earl in our car because we both knew him and think he's one of the best there is."
This weekend's event may not be a race in itself, but each and every team rolling out of the garages will be putting everything on the line in an effort to see if their respective cars are race fit. It's also a chance for teams and spectators alike to see all the cars contesting the 2017 championship on the same track at the same time.
Sure, there's been testing over the past months at Valencia, Aragon and Paul Ricard since the end of the 2016 title chase, but this is when the gloves come off for the various manufacturers. It's a chance to compare and either showcase any advantages you may have, or realise you've got a bit of work to do before the opening round of the season at Silverstone, April 16.
"I'm looking forward to the Prologue, but more so to the opening round of the championship at Silverstone in April. Having said that, the Prologue is the first time we get to see the competition at the same track, on the same weekend.
"We obviously hear rumours about how Toyota are getting on, but the Prologue will give us a better idea where we're at and they are at. The first race will be the real test but it's exciting to see what everyone's got this weekend.
"In the past we have treated it like testing and gone through our programmes. Now though, if you're not going 100 per cent you're not testing the car at its limits.
"At 100 per cent you're more likely to see problems you wouldn't have before.
"In a lot of ways you'd be foolish not to push the car to its limit. Other than the monocoque chassis, the car is brand new including engine, electrics and aero, so it needs to be pushed hard," said Hartley.
A field of 27 of the full season entries will be present at Monza for the five sessions of testing planned over two days, including a night session. While most eyes will be on the Porsche and Toyota machines, keep an eye on the ByKolles Racing Team and their LMP1 ENSO CLM P1/01-Nismo car.
They have signed up former World Rally Championship and Formula One racer Robert Kubica as part of their driver lineup.
The Pole had his first taste of the WEC and LMP1 prototypes in Bahrain at the end of last season and looks like he knows how to get the best out of these cars.
WEC calendar
April 16: Silverstone.
May 6: Spa-Francorchamps.
June 17-18: 24 Hours of Le Mans.
July 16: Nurburgring.
September 3: Mexico.
September 16: America.
October 15: Japan.
November 5: China.
November 18: Bahrain.