Please take another look; we introduced custom machine types back in November: http://googlecloudplatform.blogspot.com/2015/11/introducing-Custom-Machine-Typ

Please take another look; we introduced custom machine types back in November: http://googlecloudplatform.blogspot.com/2015/11/introducing-Custom-Machine-Types-the-freedom-to-configure-the-best-VM-shape-for-your-workload.html Which would let you adjust your RAM to vCPU ratio (as low as ~1 GiB per vCPU and up to 6.5). Disclaimer: I work on Compute Engine.