Let's get one thing straight from the very start; for all manner of reasons, not least the uncertainty over fuel loads, it is far too early to start making predictions about the forthcoming season based on today's evidence.
That said, Ferrari, Red Bull, Mercedes, McLaren and Alfa Romeo can head back to their hotels tonight knowing that at least they have reliability, and in the case of the Maranello outfit pace also.
Sebastian Vettel completed 169 trouble-free laps today, and other than a minor spin at the very start of the session, neither the German nor his car missed a beat. Not only does the car look stable, it appears to be kind to its tyres.
"Obviously it's very early, the first day, and it's meaningless in a couple of weeks," the German subsequently told reporters. "But for now, huge compliments to everyone back at the factory.
"First impressions yesterday were good and strong," he added, continued to the shakedown at the weekend, "the same today. The car is working. I feel comfortable. I certainly got enough laps today and I'm going to sleep well tonight. The guys are very happy.
"How they tackled the new rules and regulations and what they put on track today is very close to perfection in the first day of driving," he continued, "the amount of laps we did, how the team was handling the car.
"Everything is more on the edge compared to last year's car," he admitted, "tighter and so on, what you would imagine. But no major dramas, so from that point of view we are very well prepared.
"It was unbelievable," he grinned, "the car was working really well. We had no issues slowing us down, we actually completed the programme just the way we wanted. We were able to squeeze a little bit more out even."
Finishing the day second quickest is probably more than either McLaren or Carlos Sainz dared hope for, and while the Spaniard's best time was posted on the (softer) C3 rubber, the 119 laps tally is a lifetime away from the horrors of 2015.
"It looks like our hard work has paid off," said the Spaniard. "It's been a very positive start as we've been able to run without big issues, play a bit with the set-up of the car and gather data to analyse. Good job everyone, because 119 laps on the first day is a good step.
"There's still a lot of margin to improve the car," he admitted. "Following today's work, we know more clearly the direction we want to try. Now we have the information for a strong debrief, so we will keep working and moving forward."
At Haas it was an up and down day, Romain Grosjean losing track time this morning due to a fuel pressure issue, but in the afternoon he was able to put in some competitive times.
"I think we can be happy enough with our day, in terms of the car's feeling," said the Frenchman. "We didn't have a smooth run in the morning, but saying that, the afternoon went better. We had lost a fair bit of track time, but we recovered to put in some good runs. The team's done a good job again to produce a car that's very nice to drive. There's more work to do obviously, we need to understand the car, but at the minute I'm very happy with what we've got."
A great first day for the Red Bull-Honda partnership, Max Verstappen posting the fourth best time and the second best tally in terms of laps.
Late in the day the Dutchman also scored a psychological victory of sorts, when, having trailed Vettel for a couple of laps, finally nailed the German with a late move.
Though the moment is hardly likely to cost Vettel any sleep, those couple of laps running in the exhaust gases of the pace-setting Ferrari will no doubt have given the Red Bull engineers some vital extra data in terms of the new regulations.
"To do 128 laps on the first day of testing is a really good day, so I'm very happy with that," beamed Verstappen. "We collected a lot of data, which is really important, and we'll analyse everything tonight to see what we can improve on tomorrow when Pierre is in the car.
"I'll also go into detail tonight and tomorrow to see where I can improve for my second day. So far, so good and I'm happy that we were able to do so many laps. I'm looking forward to the rest of the week."
Kimi Raikkonen, on his debut proper for Alfa Romeo, bookended the day with red flags, the first caused when he spun at T5 just moments into the session and the second when his car stopped on track with just two minutes remaining.
Though not sporting the 'basic' front wing witnessed at last week's shakedown, the Alfa continues to impress many within the paddock, and with 114 laps completed the car is clearly fast and reliable and therefore a threat in what once again should be a tight midfield.
Daniil Kvyat spent more time in the pits than he would have liked, nonetheless he will be fairly pleased to end the day sixth quickest, albeit having posted his best time, like Sainz on the red-banded C4 rubber.
"It was a productive day," said the Russian, "and it's good to be back behind the wheel.
"We managed to do quite a few laps, which is important on the first day of testing to get some mileage under your belt so you can see how the car behaves.
"It's too early to draw conclusions, but I think we have a good baseline for now and we need to keep working on that. Every time we were on track it was smooth running, and everyone was operating at a high level.
"I have another three days in the car which gives us the chance to improve on the things we worked on today, so we will look over the data to see which direction we will take on Wednesday. I worked with my new engineers and we all understood each other well straight away. It was certainly a good start."
Like Max Verstappen, the Russian enjoyed some fun and games in the afternoon, when, on no less than three occasions, he found himself scrapping over the same piece of tarmac with Lewis Hamilton. Eventually, clearly tired by the silliness, the Briton left the Toro Rosso for dead on the pit straight.
It was a difficult day for Sergio Perez and Racing Point, the Mexican finishing seventh on the timesheets but with only 30 laps to his credit. The team subsequently appeared untroubled by the limited running, citing "teething problems" - among them a small oil leak.
"It was a typical first day of testing," said Perez, "with a lot of checks and not a lot of running. It was effectively our shakedown and, even though the day was a bit shorter than expected, I felt quite happy with the car straight away.
"The mileage wasn't great but I think it was still a promising start. I am happy with the performance we managed to get out of the car and with its balance. The conditions weren't great: the track was quite cold and green to begin with, but I end the first day feeling positive. It was important to start understanding the car as much as we could and for me to make myself comfortable with it as a driver."
Mercedes and Renault both split driving duties with one driver in action this morning and his teammate driving this afternoon. Interestingly, both teams stuck with the harder C2 compound for much of the day, posting their best times on the white banded rubber.
Bottas finished the day eighth quickest, but driving in the afternoon, teammate Hamilton was only 0.008s off his pace.
"I quite enjoyed this morning," said Bottas, "it's good to be back at the track. I did 69 laps and there were no major issues with the car, so it was a relatively successful run. Since the car is brand new, we immediately found ways to improve the balance and the behaviour and we will continue to work on that in the next days. It's good to see the car running well and it proves that the entire team is doing a great job, both in Brackley and Brixworth, but also here at the track. I'm looking forward to a more time in the car tomorrow afternoon.
"It's good to be back in the car," added Hamilton, "and it's great to see the car is running as smoothly at it is. It feels quite a bit different compared to last year and we're now getting to know it, trying to understand the balance and trying to understand the characteristics we're working with. It's been a positive first day, we got through our running plan and there's lots for us to learn about the new car which we will be working on.