Mercedes' Kimi Antonelli leads the cars of several rivals in F1 testing in Bahrain Mercedes' rivals have succeeded in securing a rule change following a pre-season technical row over engine performance. Audi, Ferrari, Red Bull and Honda had been pushing for a change in the regulation governing compression ratios on the basis they believed Mercedes had secured an advantage through clever use of materials technology. Formula 1's governing body the FIA said on Saturday that a change to the way the compression ratio was measured would be introduced on 1 June with a further revision for the 2027 season. A statement said the rule change had been approved unanimously by all power-unit manufacturers. The compression ratio is a measurement of the cylinder displacement between the two extremes of the piston stroke. The original rule stated the ratio would be limited to 16:1 in the new engine rules introduced this year - a change from 18:1 under the previous regulations - and this was measured at ambient temperature.…