Richard Kilty, Harry Aikines-Aryeetey, James Ellington and Adam Gemili gave a performance headed into this afternoon's conclusive session that suggests they can pursue similar returns in England vests at Glasgow 2014.
Their mark of 38.51 seconds was just off the championship record but there is more ahead. "This is a solid team," declared Kilty. "This is hopefully a team that will push for the British record."
They helped GB&NI, with 158.5 points, stay within sight of leaders Germany who, on 195, hold a margin of four over defending champions Russia.
With the UK Championships in Birmingham next weekend, room for trial and error is diminishing. Scot Eilidh Child acknowledged improvement is needed after stuttering to second place in the 400m hurdles when maximum points had seemed a certainty.
With preparations hindered by illness, her stamina went missing over the final metres to let Ukraine's Hanna Ryzhykova sweep by. "I just felt sluggish," she said. "It was hard, windy but I will try and take something from this for next week."
Olympic long-jump champion Greg Rutherford drifted down to second behind Germany's Christian Reif but Danny Talbot was boosted by his runner-up result to France's Jimmy Vicaut in the 100m.
On his senior international debut, Luke Caldwell came sixth in the 5000m with the after-effects of his long flight back from the US costing him a higher placing.
"I put myself in the right position but I didn't have the legs I expected," the Scot said. "I was sitting in the last lap thinking I have a gear to spare here but it wasn't there."
o Eilish McColgan picked up third place last night in the 3000m at the EAP meeting in Bilbao, with Bahrain's Tejitu Daba winning.
Edinburgh hammer hopeful Kimberley Reed secured a spot at next month's world junior championships in Oregon by winning the trials in Bedford with a throw of 58.13m.