I do not think it is appropriate to have a communal celebration of the Liturgy of the Hours in a car.
Some extracts from the General Instruction of the Liturgy of the Hours, from Chapter Five “The Rites to be Observed in Communal Celebration”.
“258. In the absence of a priest or deacon, the one who presides at the office is only one among equals and does not enter the sanctuary or greet and bless the people.”
“261. During the gospel canticle at morning prayer and evening prayer there may be an incensation of the altar, then of the priest and congregation.”
So the impression is that the place for communal celebration is a church, oratory or chapel. But it has:
“262. The choral obligation applies to the community, not to the place of celebration, which need not be a church, especially in the case of those hours that are celebrated without solemnity.”
The Catechism of the Catholic Church includes:
“
Places favorable for prayer
- The church, the house of God, is the proper place for the liturgical prayer of the parish community. It is also the privileged place for adoration of the real presence of Christ in the Blessed Sacrament. The choice of a favorable place is not a matter of indifference for true prayer.
- For personal prayer, this can be a “prayer corner” with the Sacred Scriptures and icons, in order to be there, in secret, before our Father.48 In a Christian family, this kind of little oratory fosters prayer in common.
- In regions where monasteries exist, the vocation of these communities is to further the participation of the faithful in the Liturgy of the Hours and to provide necessary solitude for more intense personal prayer.49
- Pilgrimages evoke our earthly journey toward heaven and are traditionally very special occasions for renewal in prayer. For pilgrims seeking living water, shrines are special places for living the forms of Christian prayer “in Church.”
And from the “In Brief” section:
- The most appropriate places for prayer are personal or family oratories, monasteries, places of pilgrimage, and above all the church, which is the proper place for liturgical prayer for the parish community and the privileged place for Eucharistic adoration.”
With the distractions that there will be in a car it seems to me to be a particularly inappropriate place for a celebration of the Liturgy of the Hours.
[Excerpts from the English translation of the
General Instruction of the Liturgy of the Hours , as published in
Documents on the Liturgy 1963 - 1979 (Liturgical Press, ©1982, ISBN 0814612814 ), © 1974 International Commission on English in the Liturgy. All rights reserved.]