Christian Horner has questioned the progress made by Red Bull's rivals since the start of the season, notably Mercedes following the unveiling of what he claims is “a B-spec car”.
After team principal Toto Wolff lamented the performance of the W14 in the opening qualifying session of the season in Bahrain, the team decided soon after to alter its development direction.
A raft of upgrades that included a new front suspension, floor, and sidepods were recently revealed at the Monaco Grand Prix.
At a more representative circuit such as Barcelona's Circuit de Catalunya, Lewis Hamilton and George Russell conjured Mercedes' best result of the season on Sunday by finishing second and third in the Spanish Grand Prix.
Hamilton, however, was still 24 seconds adrift of race-winner Max Verstappen who has scored five wins from seven races this year and is firmly on course to secure a third consecutive drivers' championship.
Running the rule over the updated Mercedes, Horner said: “For sure they've made a step.
“They've introduced pretty much a B-spec car – so they must have used a significant proportion of their development budget on that.
“But when I look at the gap at the end of the race it is very similar to where it was in Bahrain.
“All that's happening is the running order behind us seems to vary from race to race – you know, Fernando (Alonso) last weekend (in Monaco), Mercedes this weekend.
“It will be interesting to see how that plays out over the next few races.”
(article continues below video)
Red Bull's dominance comes in the face of its punishment last year for breaching the new cost cap regulations.
Aside from a US$7million fine, the team was also hit with a 10 percent reduction in its aerodynamic testing capability, affecting not only the development of this year's car but also its 2024 model.
Despite the penalty, Red Bull remains untouchable, to Horner's obvious delight.
“Of course, we have to balance the ATR (aerodynamic testing restrictions) for this year and for next year with the development that's currently going on,” said Horner.
“But the way we are strategically using the ATR, the team is just doing an incredible job, being extremely efficient. You can see we've very subtly developed the car since Bahrain.
“We've seen others bring significant upgrades now and the margin has remained pretty much the same from where it was in Bahrain.
“So that's hugely encouraging to everybody in Milton Keynes who is doing an outstanding job at the moment.”
There is no doubt the gaps between a winning Red Bull – it has won all seven races this year – and the best of the rest has been significant.
Removing the crash-strewn ending to the Australia Grand Prix and the fact it finished under safety car conditions, the other six races make for interesting reading, and Horner needs to be more mindful of the progress Mercedes has actually made.
In Bahrain, Red Bull was crushingly dominant, with Fernando Alonso back on the podium on his debut for Aston Martin, albeit 38.637s adrift of race-winner Verstappen. Hamilton was Mercedes' lead driver that day, 50.977s adrift.
The Bahrain International Circuit is fast and predominantly flowing, with numerous medium- and high-speed corners, not too dissimilar now to the Circuit de Catalunya following the removal of the tedious chicane in the final sector.
The conditions on Sunday certainly played into Mercedes' hands as there was almost constant cloud cover, reducing air and track temperature, and providing an ideal operating window in which the W14 could operate on the various Pirelli compounds.
The gap between Verstappen and Hamilton at the flag was 24.090s, half that in Bahrain after the 300 kilometres.
Horner may have sniffed a little at Mercedes for using “a significant proportion of their development budget” on its upgrade but it is evident progress has been made by the Silver Arrows.
Mercedes is rightly being cautious as to its performance in Spain, with the next few tracks in Canada, Austria and Britain providing a more balanced view.
For now, though, cutting the deficit to Red Bull by half – even if it remains considerable – is none too shabby from the ‘B-spec'.