It seems that the values that were added in "Car Dash" mode in FM7 were moved towards the end of the Horizon 4 packet. The structure of the Horizon packet is:
[0]-[231] FM7 Sled data (as mentioned before)
[232]-[243] FH4 new unknown data
[244]-[322] FM7 Car Dash data
[323] FH4 new unknown data
I'm using the following C# code to get a new byte array that has the same structure as a "Car Dash" packet in FM7:
if (rawTelemetryData.Length == 324)
{
byte[] newData = new byte[311];
Array.Copy(rawTelemetryData, 0, newData, 0, 232);
Array.Copy(rawTelemetryData, 244, newData, 232, 79);
rawTelemetryData = newData;
}
I'm not using all the available information in my program, so I'm not sure if all of this is correct.