PICO says the TA386 200MHz probe is an upgrade to the TA375 100Mhz probe. Is there any disadvantage with using the TA386 instead of the TA375 probe with any of the automotive scopes?
Either of these probes are more than sufficient for Automotive scopes with 20 MHz bandwidth.
You could argue that the higher bandwidth probe (TA386) may reveal more noise than the TA375 but this is certainly no disadvantage and can be resolved with filtering if required.
Either, or are fine in this scenario and having the additional bandwidth could be useful if you change to a higher bandwidth scope from the T@M Range
For more information on high impedance high bandwidth probes take a look here