Depending on how you choose to measure it, Mazda's Wankel rotary could be as big as 2.6 liters already, but to most people, the engine has always been 1.3 liters. While the engine has never been known as a fuel-sipper, it has always been known for its excellent power-to-weight ratio. With the last update of the venerable design, Mazda offered up a partial solution to the engine's past emissions and oil-consumption woes by controlling the oil injection via a computer. We had an RX8 in our family which barely used any oil at all. Being suckers for technology, my family is always ready to try something new, and the power output of the rotary was plenty for our purposes. The rub was always keeping the engine under 4000 rpm or so. You see, there are extra valves which open at preset rpm levels, regardless of how much power the engine really needs to make. So, when kept under the point where the first extra set of valves open up, the engine consumes much less fuel.
Here is an article which claims that the next rotary from Mazda, the Renesis 2, will be enlarge somewhat. This could open up the possibility of extra power for one, but could also allow engineers to allow for better mileage under low-throttle conditions, which would be a big step in the right direction. If any Mazda engineers are reading this, flex-fuel capability would be nice too! We may find out more details at the Tokyo Motor Show in a few months.
[Source: Rotarynews via Autoblog]