Tbh Frosty, if you change your cars every three years as mentioned earlier, then I wouldn't expect any issues such as needing to regas. One thought does always occur to me and that is that new vehicles that stand around waiting to be sold (and of course same applies to second hand vehicles) potentially could lose a significant amount of refrigerant due to inactivity. Its a pity that there isn't an easy check on levels at the point of sale.