been making an effort to keep it at 55 mph

And my latest mpg estimate came to 43.3! Driving a 2000 Toyota Echo with not quite a quarter million miles on it - mostly open road driving (rural, non-highway, interspersed with small towns). I’ve also been making an effort to take foot off the gas pedal when it looks like I might need to slow down ahead. Been putting her in neutral (4 speed automatic) when stopped for prolonged periods (red lights, construction).