Either that or the daylight savings setting needs to be changed.
I had this for ages, i went to the time and date settings and selected, set time & date via internet, rather than set manually, and it cured the problem.
99% positive that I set my PS3 time via the internet and my timezone is correct.
I've had my ps3 for about 3 years now and this only happened with GT5 and it wasn't until recently.
I'll confirm that my PS3 settings are correct in a few hours.
But for the sake of time, let's assume that my PS3 settings are correct - is there anything else I can do?
I have the same problem and it is not connected to system time. For some strange reason, GT5 time is one hour ahead of system time (time and time zone are correct). Right now, GT5 says it's four o'clock (east coast US) but my system says it's 3:00 PM.