I agree with most of this, but I'd add that they likely did use a few new hardware components (testing items to be further refined for 2020) that were new for this "Spec 4." They ended up using 2 new ICE units over the weekend, as the first suffered a pneumatic leak. The second ICE unit completed FP3, qualifying, and the race.dans79 wrote: ↑Mon Dec 02, 2019 5:57 pmted kravitz mentioned something on air during one of the sessions this weekend, and i assume a lot of other people just copied or paraphrased what he said.
I don't remember exactly what he said, but it was based on a conversation he had with Andy Cowell. I believe it was something along the lines of Bottas was using an engine that used some concepts similar to the 2020 spec, and that would be worth up to 2 tenths a lap.
My interpretation of this, would be that they ran a 2019 spec 3 engine with 2020 spec 1 software/mappings. Running an actual 2020 spec motor is unlikely in my opinion as it would most likely require different packaging and cooling, since Mercedes is rumored to be making a big change.
In sum, we can call these final iterations '19 Spec 4 engines because of different hardware/software configurations compared to previous Spec 3s.
But I agree, to call it a 2020 PU would be a step too far. Especially as there is an architecture change coming for 2020.