I think your cats will hate it, especially if they are older animals and not used to cars. Our first cat was traumatised by car journeys. When he died and we got a new kitten, I regularly took him for short car journeys when he was a baby so he became accustomed to it and for many years he was fine, usually sleeping on the back seat throughout the journey.. Then one week-end for the first time we had to board him in a cattery as our neighbour who normally looked after him was in hospital. Thereafter he always associated a car journey with his awful time in a cattery and yowled, vomited and wet himself every time he was put into a car. Even taking him to the vet then became a traumatic experience for all of us. I think it's far better, if your cats are not used to cars, to try and find a neighbour or nearby teenager who wants some occasional pocket money to care for them in their own home, or if this isn't an option, settle for a cattery, especially if they can be boarded together for some extra reassurance. Housesitting?petsitting agencies are also a possible option, but normally quite expensive.