Hmmm, that is strange, I got one myself - it went up to 8 mins when I went for an hour long drive (with not much stop/start). If its only 30 mins and you are doing 100 all the way, it depends how often you go slow or are stopped. Usually, when the revs are below 2000 the time count down (or it should count down). So if you are above 2000 for the majority of the way back (never stopping/slowing etc) then it maybe is possible to go to 5 mins.