efficiency expert
efficiency engineer

Most economists and efficiency experts, after studying modern energy use, have come to similar conclusions.

He advertises for an "efficiency expert" to come help him turn things around.

"They are sending an efficiency expert out here to examine our operation."

Without our little efficiency expert, Carla, everything would just go to hell.

"What do you have to know to be an efficiency expert?"

"That's what I came in to see," said the efficiency expert.

He had obtained employment in my father's plant as an efficiency expert.

What we used to call an efficiency expert in the old days.

No efficiency expert will ever tell you to tour with a big band.

It's nice to share designs and hope that efficiency experts will improve on these.