less than a threshold while the vehicle is propelled via motor torque only, rotating the engine unfueled via the motor torque at less than cranking speed to sequentially heat all engine cylinders as they pass through a compression stroke while at least partially throttling a valve disposed in a passage coupled between a first exhaust manifold and an intake passage, the first exhaust manifold coupled to a first set of exhaust valves. In this way, the engine cylinders may be heated via recirculating warm air generated via a compression stroke of the cylinders while they are being rotated at the less than cranking speed. Further, by at least partially throttling the valve, the required cranking torque may increase, thereby further increasing heat to the engine and warming upon 1 June 2012.

The highest proportion of articles was published in 2008 and then the average number of articles remained relatively constant. The number of articles published each year was: 123 articles (8%) in 2005, 140 (9%) in 2006, 221 (15%) in 2007, 255 (17%) in 2008, 242 (16%) in 2009, 244 (17%) in 2010, and 233 in 2011 (16%). The data used to classify the research design were reported in the title or abstract in 1,145 articles (78%), but the full-text had to be consulted for the remaining articles (313, 21%). The majority of articles (1,286, 88%) reported human research. Animal/cadaveric research was reported in 79 articles (5%), and the remaining 93 articles (6%) were editorials, comments, reflections, letters to the editor, etc., which could not be