The phrase "an even more efficient" is correct and usable in written English.
It can be used when comparing the efficiency of two or more things, indicating that one is more efficient than another, and that the difference in efficiency is significant.
Example: "Our new software update provides an even more efficient way to manage tasks than the previous version."
Alternatives: "a significantly more efficient" or "an increasingly efficient".
And he said Moscow was trying to modify smallpox into an even more efficient killer.
Observe his smug grin when Megan becomes an even more efficient and effective version of him at work.
If the new bulb passes the department's testing regimen, it will be an even more efficient, longer-lasting lighting device than today's compact fluorescent bulbs.
Improvisation is a trafficker's greatest asset, and in recent years, Sinaloa has devised an even more efficient solution to the perennial challenge of getting marijuana across the border.
"You'd be improving the government's balance sheet in an even more efficient way," said Lawrence B. Lindsey, the former Federal Reserve governor who is Mr. Bush's chief economic adviser.
I have often thought what genius it would be to develop a midlife fear of flying, or a fear of public restrooms, an even more efficient way of making sure you won't go anywhere.
Open source and software-as-a-service create an environment that allows even more efficient creation of products and companies.
The NHS has improved its estate management but could save a further £1bn a year by becoming even more efficient in managing empty or underused space.
The new kinetic scheme not only preserves favorable properties of the existing BGK NS method, such as stability, high resolution, and good performance in capturing discontinuity, but also achieves a very high efficiency, which is even more efficient than the same order well-defined classical finite difference scheme based on the macroscopic governing equations directly.
Depending on the lab in question, upgrading a freezer could be even more efficient than expected.
Furthermore, increasing scrutiny and accelerated approval pathways provide a driving force to be even more efficient with limited regulatory resources.
