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A novel transaxle configuration combines two main concepts. The first of these achieves spacing of six forward and two reverse gear ratios that is unparalleled for a planetary geartrain. The second concept keeps the transaxle from being any more complex than current production four-speed transaxles, as well as providing ancillary benefits such as enhanced torsional damping and improved durability of planet pinion bearings. Also presented is a powertrain configuration that utilizes a “T-drive” variation of the six-speed transaxle, but with its horizontally opposed engine mounted longitudinally.

A new transmission concept utilizes only a single sprag or roller clutch for automating all power-on downshifts, including all possible combinations of out-of-sequence downshifting. Power-on downshifts would, in addition, be executed much more quickly than in current automatic transmissions. Upshiftlng once under way would, in contrast, be manual, but with enhanced gearshift and clutch action which would help win converts from motorists who normally prefer automatic transmissions. Other features of this new concept include reduced cost, smaller transmission size in comparison to current manual transmissions and more speed ratios and more flexible spacing of ratios in comparison to typical automatic transmissions.

Many automotive engineers do not associate drive-by-wire control with any improvement whatsoever in fuel economy. Nevertheless, computer simulations have now been based on stationary engine dynamometer testing of a recalibrated production engine, and these simulations of actual driving strongly suggest that fuel economy improvements in the area of 10% will result from utilizing a drive-by-wire approach which employs several novel features. Notable among these features are a dual wide-open-throttle engine calibration originated for use with continuously variable transmissions and a transmission shift control strategy which relies on electronically stored engine performance data in lieu of any form of transmission shift map.

Maximum fuel economy and Low exhaust emissions can exist together if a predominantly wide-open-throttle engine operating schedule is used to complement a continuously variable transmission. Moreover, the concurrently required engine re-calibration often entails less effort than the more usual fuel consumption and emission mapping procedure.