# The Indicator of GDI Engine Operating Mode and Its Influence on Eco-Driving
## 5 The Results and Discussion
The opposite effect can be observed for the percentage share of driving using a homogeneous mixture. The sum of the average active injection times per one kilometre (\(\Sigma t_{ii,an;k}\)) increases with the percentage share of homogeneous mixture mode of engine run. It is represented by red points approximated by the same colour line (Figure 14). The presented relationships are confirmed using the correlation coefficient calculated for them, at least 0.92. The answer to whether the driver's information about the mode of engine run results in a more economical driving style is given by results shown in Figures 7 and 13. In the case of test nos 10-18 (the driver had access to the information about the mode of engine run), the highest share  
Figure 7:3 The standard deviation of the engine speed (**a**) and the vehicle speed (**b**). Figure 7:4 The percentage shares of modes of the GDI engine run for all tests carried out in the experiment (\(S_{m}\)). of driving time with the stratified mixture use and the sum of the driving time with the stratified mixture use with no injection was observed. During the first nine tests, in which the indicator was covered, the lower timeshare of the economic fuelling of the engine was noticed. Only test no. 4 gave a similar percentage of the economic mode of the engine run as for tests with the use of the indicator. The average share of fuelling the engine with a stratified mixture with the covered indicator was 43.1%, while when the indicator was visible to the driver, it was 58.5% (Figure 13). Thus, the share of fuelling the engine with the stratified mixture increased due to the information from the indicator, and it raised by over 15% on average. For these two parts of the experiment (nine tests driving without and the nine with the information from the indicator), the difference in average fuel consumption measured directly for both parts was 10.4% in favour of the part of driving with the indicator information available. The registered data from the indicator (Figure 15a) show how the driver, without the information about the type of mixture, tried to find an economical way of acceleration pedal operation (Figure 15b). Unfortunately, these trials did not bring good results. Lack of information about the mode of engine run caused the driver to use the accelerator pedal constantly to regulate the driving speed. It resulted in a persistent change in the engine run mode, so the green and the red signals appeared alternately. In such driving, a momentary injector shut-off occurs much more often. The constant change of the type of mixture gave a more significant share of supplying the engine with a homogeneous, less economic mixture. For 33.7% of the route presented in Figure 8, the driving used a stratified mixture. For as much as 52.4% of the route, the driving used the homogeneous mixture, and 13.9% during engine braking (the air only). Figure 15b shows the opposite situation. A driver who has information about the mode of engine run can easily drive a huge part of the route while supplying the engine with a stratified mixture (more economical one). The data presented in Figure 15b (test no. 11) show that the driver completed the distance in 73.4% of engine fuelling with a stratified mixture and 21.8% with a homogeneous mixture. The remaining 4.7% of the driving time was covered with engine braking. The information from the indicator enabled operating the accelerator pedal so that the engine was supplied with the stratified mixture in a controlled way. In practice, this requires quick acceleration to the target speed and then setting the accelerator pedal to a position where the indicator confirms that the engine was supplied with a stratified mixture, and it is possible to maintain the correct car speed. Figure 7:5 The sum of average active injection time per one kilometre (\(\Sigma t_{ia,a;b;t}\)) vs. percentage share of the engine being supplied with a different type of mixture (\(S_{m}\)).