Red Bull’s Formula One B-team Toro Rosso appeared to win the stand-in jackpot when reigning Le Mans winner was available to drive for them at the United States Grand Prix. Only catch is, it’s been five years since he’s even driven a single-seater, much less a Formula One car.

There wasn’t time for Hartley to have fit in a test drive before this weekend, as he says that the decision to let him drive happened very fast. Hartley told the yesterday that he was just now meeting some of the team members this week, and didn’t even have his seat insert made for the car until Wednesday.

But much like F1 fans followed Fernando Alonso’s run in IndyCar, I, an admitted Porsche fan, am all about in Hartley’s run in F1 this weekend. The 919 team is too good and I’m devastated that it’s shutting down. Those drivers are still our Porsche dudes. I’ve found myself actively rooting for them to score good rides elsewhere next year so they’ll still be out there, driving for our amusement.

Then there’s the eternal question that comes up any time these cool crossover drives happen: how do drivers from other disciplines really compare with each other when they’re in the same car? Some, like Alonso, seem to be fast in anything. How is Hartley?

Hartley landed this weekend’s F1 drive after reaching out to Red Bull F1 advisor Helmut Marko when he learned of the 919 team shutdown, but he didn’t get an immediate response, as he explained in yesterday’s press conference:

Actually, when it was announced that Porsche would stop endurance racing in LMP1 for next year, I called Helmut Marko and I said: “Look, I’m a different driver than I was 10 years ago, I’ve learned a lot, and if there is ever and opportunity I am ready.” He didn’t say much, he just said he got the message, and three months later he made the call. This happened very quickly. I didn’t know about it much sooner than the press did. It’s been quite a whirlwind of a couple of weeks to arrive here.

Hartley has been driving fast Le Mans prototypes that certainly compare in speed to Formula One cars, but hasn’t had any single-seater experience in a very long time.

Hartley explained that he started off gunning for F1, but felt like he wasn’t ready for the pressure at the time:

I guess I wasn’t ready. I had some success in the early days, I won the Formula Renault championship, I became the reserve driver, had my first F1 test at 18 years old and I guess I just didn’t deal with the pressure. I stopped enjoying it, I wasn’t happy; I was pretty young and away from home. When the Formula One dream, so to speak, stopped in 2010, I picked myself up, I found endurance racing and yeah, I have learned a lot from that experience.

Formula One didn’t pan out for him then, but his move into sportscar racing did—and Hartley believes it set him up to deal with the pressure of driving in F1 just fine:

Being in the LMP1 programme, a high-profile category, where there is a lot of pressure, probably not that dissimilar to Formula One in some ways, in that respect, in development of the race car, and working with team-mates has been great. I’m a lot stronger than I was back then, basically. I wasn’t ready at 18 years old. I like to think I’m ready now. I’m not very prepared for this weekend, I haven’t the car, I haven’t driven a single-seater since 2012, but I like to think that Porsche LMP1 has hopefully prepared me well.

Fortunately, Hartley has also been driving sportscars at Circuit of the Americas since 2013, so he knows the track. The harder part, he explained, will be learning how to drive this year’s F1 car:

Actually, as a racing driver, learning a track, when you have enough experience, it can happen quite quickly. I think learning the car will be the bigger challenge. The big tyres, the big downforce that these Formula One cars have at the moment, obviously they are setting lap records at every track they go to. Yeah, I’m going to have a bit on my hands tomorrow and the track is only a small part of it.

So far, his first Free Practice 1 laps in a single-seater since 2012 have been going just fine. Admittedly, Free Practice 1 is a tinkering time as much as it is a practice run for the drivers, so it can be hard to gauge how a team will do based on their practice laps. But Hartley has been running solidly mid-pack, which is incredible against drivers who’ve been primarily dedicated to single-seat formula cars for years.

Then there’s the fact that Formula One cars are often built around a specific driver’s preferences. So Hartley must get back up to speed on single-seater driving in a car built for a completely different driver. That’s tough.

Naturally, Hartley’s surprise F1 drive has opened up all kinds of speculation as to where he might be going next year. Hartley has been heavily rumored to be looking at IndyCar, but his ties to the two Red Bull F1 teams are also strong. He even sought advice from Red Bull driver Daniel Ricciardo and former Red Bull F1 driver Mark Webber on how to drive these cars. However, he said that he still doesn’t have plans nailed down for next year.

“Nothing has been said by the team, and also, going forward nothing has been said yet,” Hartley told the press room of his 2018 plans.

: Free Practice 1 results can be found . Hartley ran 14th fastest.