I have noticed that between the speeds of 40-60 mph, there is a vibration in acceleration. It does this when I've been driving for a while, approximately 30 mins. It feels as if the engine speed is faster than the rpms. I have an 08 with 145,000 miles on the car. No warning lights appear on the dash. I know the ES has a sealed transmission, I hope it's not the tranny, anyone else had this issue?

 

You can check the cv axel. Make sure there is no leak of grease on the axel. And check the tire balance also. The axel can make the transmission vibrate. The worn old tires make the entire car vibrate

 

 

I had the tires replaced today, hoping it was a balance issue due to worn tires, the vibration is still there. A few months back when I was getting an oil change, the dealer said the passenger side CV joint was going bad, but I thought bad CV joints make that tale tale metallic clinking and clicking noise which I don't hear.