R/P ratio is the current proven reserves (barrels) divided by the current production rate (barrels per year). The result is the timespan (years) that the reserves will last.

I've fit a straight line to historical production data and concluded that oil will run out around 2032, much sooner than the R/P ratio suggests. But that is assuming that production can be increased steadily to match consumption without any interruption, and that reserves stay the same.

However, improved technology has, for the last several years, allowed reserve estimates to be increased at roughly the same rate as production, keeping the worldwide R/P ratio steady at just over 40 years. So there is no obvious downward trend worldwide. Although there are still the obvious downward trends for USA and Mexico, as well as obvious upward trends for Brazil, Eurasia, Middle East, and Africa. Regardless of worldwide trends, or the lack thereof, the regional trends should spur people into action. That is, to drive cars that consume less fuel.