Enable Arduino LEDs when the gap to the car behind is less than XX seconds in iRacing

Hi, I've successfully configured SimHub to connect to an Arduino that has a bunch of WS2812b leds. I already added effects for left/right car, yellow flag ... it works great!

Now I would like to have the following scenario: when in iRacing the gap to the car behind is closer than for example 3 seconds, I would like to enable/flash some lights. I thought I could do this with "when formula is true" effect, and the NCalc formula: 

[PersistantTrackerPlugin.DriverBehind_00_Gap] < 3000

Unfortunately it seems that the DriverBehind_00_Gap property only gets updated when a lap is completed. Is there a way to get realtime info on the gap to the car behind? (like a dashboard is continuously displaying the gap to the cars behind/in front) 

Thanks again,

Jan