Download and install the VB6 runtimes and extra components as linked to from here: http://www.vehicle-analyser.com/download.html
Two things to consider here.
1. The custom searches will always return a time that is slower by the timestep due to the subtraction of the two times that is necessary to set a minimum speed. This shouldn't be an issue. There is something wrong that is throwing those figures off; I'll have a look.
2. For top speed, the last few tenths take forever to reach (especially for low powered, heavy cars), so there will be large time differences for small changes in speed. Also the top speed used in the automated search is to a higher level of precision than you can enter (it is rounded for display in the GUI but will really be to 10 decimal places or so - whatever 8 byte floats allow). Also worth noting that there is a 120 second cut off point in the simulation, so times can never go above that.
I'll do that only once it is done, still fixing the odd bug and adding the licencing system.