Does B have the right to continue driving one (or both) vehicles until the divorce?
Can A remove B from their auto insurance and force B to get their own?
Is the answer to 1 or 2 different if B has custody of an infant from a prior relationship? (Could the use of a vehicle be deemed a
necessary "support" if there is an infant involved?)
A partial answer, since I am not familiar with some of the fine points of Connecticut law. This partial answer also explains why there may not be much case law on this point in any state.
Very early on in divorce proceedings (from a few days to a few weeks into the case if there are urgent disputed issues of support for a spouse or urgent disputes concerning custody) there is typically a "temporary orders" hearing that resolves questions like (1) and (2) on a case by case basis, at which a judge would almost certainly grant the spouse permission to use the car and insist that husband keep car insurance in force for wife.
With regard to (1), in Colorado, if permission were revoked to use the car, that might be effective, but only until a temporary orders hearing. I don't know if Connecticut would apply the same rule pending a temporary orders hearing.
But in either state, a husband who attempted to withdraw permission granted during the marriage to use a car in the time period until a temporary orders hearing in the situation described in the question would be totally fucked later in on the proceeding if he did. A judge has extremely wide discretion to make decisions at temporary orders and permanent orders and almost every judge would be seriously disgusted by a husband who acted that way (unless there was a good reason such as the wife having her license revoked, or facing a pending revocation for traffic law violations, or a recent accident, or driving drunk with a child in the car). In the case of an affluent family, a "dick move" like that would probably cost the husband hundreds of thousands of dollars in a typical case at permanent orders (even if it was remedied in temporary orders only a few days later) and would probably also lead to a seriously negative outcome for the husband on any custody issue, if there were children involved, because it would reflect a disregard for the best interests of his children at an almost psychopathic level in the eyes of a judge.
With regard to (2), this is specifically prohibited by an injunction that comes into force automatically and immediately by either party's filing of a divorce petition in Colorado. So, in Colorado, the husband could go to jail for contempt of court for doing that. I don't know if Connecticut has a similar provision. This too would also lead to huge blowback directed towards the husband from the judge at temporary orders and permanent orders in almost every case, even in the absence of an injunction. Judges are positively wrathful towards husbands who mistreat their dependent soon to be ex-spouses.
With regard to (3), this wouldn't have much of an effect if any. Support is normally set in permanent orders or temporary orders and the duty of support would run to the spouse and not to the infant. (Although the formal definition of infant is less than one year old, and if the infant was from a prior relationship that would imply a very short marriage indeed.)