Employers asked to defer a decision until a full National Joint Council meeting on 8 October when a final decision would be made.
The Unison ballot will be on a refusal to use any form of transport - a major escalation in the dispute which has seen staff banning the use of their cars since 19 July.
Employers at a meeting of the joint car allowances yesterday felt unable to accept the package worked out by the two sides 'because of political differences on their side'. Unison accepted the package after 260 branches had said 'yes' and 33 'no'.
'A ballot on escalation involving refusal to use any form of transport will now proceed and current industrial action will continue. If employers decide to renege balloting will take place this month.'
Unison members have been asked to lobby their own employers' unilateral decision to tear up the national agreement on allowances which had been in force since 1946. This move slashed car drivers' compensation.
Under the terms of the package, existing users would be protected until March 1996 with updated allowances. The vast majority of existing users would get an increase. A different scheme would be introduced for new users.