Hi.

I have a 2008 Honda Accord V6. It has done about 95,000 Kms and in great condition.
The car shakes when I drive normally between 40 and 60 kms and is less obvious at higher or speed. All services are up to date and tyres are in good condition.
When I drive in S gear, then the problem completely goes away, however I don't want to drive in this mode all the time.

Three Mechanics have not been able to diagnose the issue correctly. They suggest it may be Transmission but I am not convinced. Gear box oil change a while ago and quite clean.
No lights flash on the dashboard and engine mounts are good. Also, suspension is good too.

Any idea?