Intelligent optimum-gear indication system

Method of intelligently determining and indicating the gear of a motor vehicle drive which optimizes fuel consumption without decreasing the drive power, comprising the steps of:

• (a) measuring the driving speed (n.sub.1) of the vehicle (10) and the engine speed (n), and determining, from the ratio of said speeds, which gear (g) is engaged at that time;
• (b) continuously storing in a short-term memory (23) the instantaneous measured values of the driving speed (n.sub.1) and the engine speed (n) as well as the gas pedal deflection angle (.phi.), said engine speed and deflection angle values (n, .phi.) together defining a working point pair (A1, A2, . . . );
• (c) deriving from the values of the driving speeds (n.sub.1) measured in brief succession, a standardized power value (Pn) and temporarily storing said power value;
• (d) after each completed upshifting of the transmission (12), deriving a new standardized power value (Pn.sub.2) and comparing said newly derived value with the standardized power value (Pn.sub.1) determined prior to the upshifting;
• and (e) testing whether the new standardized power value (Pn.sub.2) is at least equal to said value (Pn.sub.1) prior to the upshifting, and, if so, copying from said short-term memory (23) the values, for engine speed (n) and gas pedal deflection angle (.phi.) which were measured and stored therein prior to said upshifting, into a threshold value memory (24) at a working point location (A) associated with the gear (g) out of which shifting has been performed,
• (f) defining, for the gear (g) out of which shifting has been performed, as an engine operating zone (II) that is unfavorable in terms of fuel consumption, all working point pairs in which the engine speed is greater than said copied engine speed value and the deflection angle value is less than said copied deflection angle value;
• and
• g) signaling on an upshift indicator (25) the desirability of an upshift each time after said instantaneous values define a working point (A) falling within said unfavorable fuel consumption zone (II).