I have a 2009 Pontiac Vibe AWD with a little over 95k miles on it. I love the car. I have experienced an intermittent gripe with a groaning/harmonic noise. I really can't tell if its transmission or exhaust and i don't have a better way to describe the noise but it only happens at one time during driving. It happens when its cold out usually, not in the warmer months and @ 39-41mph give or take. The tach is usually at 1700-1800 rpm. It feels like the car doesn't like to go that slow and as soon as I accelerate and exceed 2000 rpm the noise goes away. It is more likely to happen on an incline in the road. I never have this issue at any other speed range which is annoying because most of the posted speeds on my way to work are 40 mph. No check lights are illuminated on the dash.
Has anyone else ran into this or have an idea where to start? A local mechanic said it sounds like a nuisance fault. Any help will be appreciated.