Lewis Hamilton has outlined the key weakness that affected his Mercedes Formula 1 car at the Spanish Grand Prix. Mercedes endured a tough start to the season when the W15 did not provide the improvements they hoped out of the box for Hamilton and George Russell. The team has slowly improved its fortunes by bringing a consistent amount of upgrades to their car, with their most recent introduced at the Canadian Grand Prix. Technical director James Allison cautioned that he did not expect Mercedes to be “right at the front” in the races after Canada, but their performance is proving to be better …