I have (I think) debugged the accel test function to the point where it can be included in the JSON output routine.
Accel Test (also known as drag race) may be entered by pressing and holding down the center button.
Once there, an accel test may be armed by again pressing and holding down the center button until "Drag Ready" shows up. Once the accel test is armed, it will start once the vehicle starts moving. Once you have passed one of three selected tripwires, that portion will be acknowledged on the screen as one of the following:
"At Drag 1/2 Speed"
"At Drag Speed"
"At Drag Distance"
When all three tripwires have been passed, the accel test finishes with "Drag Finished".
If the vehicle is moving when you try to arm the accel test, you will get the message "Stop Vehicle". If the vehicle engine is not running if you try to arm the accel test, you will get the message "Start Engine".
If, at any time the accel test is either armed or in progress, the vehicle comes to a complete stop, the accel test will be canceled and the message "Drag Cancelled" will appear. Also, if the engine stops running (like if you happen to go into EOC), the accel test will be canceled and the message "Drag Cancelled" will appear.
Finally, if you again press and hold the center button long enough, the accel test will be canceled and the message "Drag Cancelled" will appear.