You can get driving directions, fairly realistic times, and estimated costs (fuel and tolls) from www.viamichelin.com which is usually better than Google, and in this case suggests a driving time of 75 minutes.
Considering that all but 10 km of the journey is on autoroute with a speed limit of 130 km/h, this might be possible if there is no other traffic. As you will be driving out of Paris when most people are driving in, you might make this sort of time.
Bear in mind, however, that a TGV will take you from Gare de l'Est to Reims in 45 minutes, and that driving out of Paris from Gare Montparnasse is not something I would recommend if you are not used to driving on the right.
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