The distractive effects of mobile phones are well documented, but the recent development of mobile phone apps that provide speed advisory warnings raises the possibility that this technology may be used to improve driver safety in older vehicles. We examined the effects of an intelligent speed advisory (ISA) app on driving performance in a simulator. One hundred and four participants (mean age = 35.52 years; 52 male) were allocated to complete the drive with the ISA app in one of five modes: active audio visual (n = 22), active visual (n = 22), passive audio visual (n = 21), passive visual (n = 21) or control (n = 18). Another 19 participants (mean age = 27.53 years; 8 male) completed the study wearing eye-tracking glasses. Participants drove a simulated 26.4 km section of rural road which incorporated typical hazards and three speed compliance zones (100 km/h, 80 km/h and 60 km/h speed limits). The app led to good compliance with the posted speed limits, particularly during the 60 km/h road segment, where the control group drove at significantly higher speeds than the groups with the ISA app. No significant differences between the four versions of the ISA app were observed, either for speed compliance or the number of speeding alerts received. Across the entire simulated drive there were relatively few glances at the app with an average glance duration of 190 ms. The ISA app did not lead to any negative effects on driving performance; lane keeping was maintained and it did not impede participants’ ability to overtake vehicles. These findings suggest that when properly configured ISA apps have a demonstrable safety benefit and do not produce adverse distractive effects. The greatest challenge may be encouraging drivers’ to use them appropriately and consistently.