I would say that rule would work well. By using the condition 'Status Data Diagnostic "Acceleration side to side" > __G or Status Data Diagnostic "Acceleration side to side" > -__ G and Speed > __mph', would be your best bet for your swerving rule. This rule is somewhat like your possible accidents rule but will only break with side to side acceleration over a certain speed.
1) To do so go to Rules & Groups > Rules > Add > Create the Name for the rule and select the "Conditions" tab.
2) Under conditions you will be setting "Add Engine" > Measurement or Data > type Acceleration side to side and select the measurement which you can change under "ADVANCED CONDITIONS EDITOR".
3) Then go to More > select "or" > repeat step 2 with Neg (-) in front of measurement under "ADVANCED CONDITIONS EDITOR"
4) Last step is to Go to More > select "and" > "Add Speed" > Save.