Originally Posted by
blitzen
Will have short(ish) connections JFK-LHR-HAJ and then ARN-HAJ-EWR and was wondering if car service would come to the rescue in case of delays (as I wouldn't have to pass immigration into the UK)
Probably not.. You don't have to go through immigration when connecting at LHR and remaining airside, but you still need to do security so that complicates things.