Milk to Go

The cases keep for a really long time, so you could always buy it and just bring with you what you need for the car ride. If you think you'd use up a case within a year, it's worth it.

Otherwise, pack a small cooler and just bring a regular container of milk and a sippy cup.

Trader Joe's is a good source. They carry the little boxes and are much more reasonable (even if not cheap) than most places. We used them all the time for car rides too. After a while, I just invested in a really good quality thermos (with a glass liner) for trips under a day. For longer trips, we take the boxes or refill the thermos as we go.

Just freeze it right in the bottle or sippy. Pack them in a cooler and set one out to thaw every few hours.

Amazon.com has milk boxes by the case you can buy.....it saves you a bit. The particular case I looked at was Horizon Organic. I only buy organic milk, so it is a little pricier anyways, but worth the money for me to not buy milk with hormones, etc for my little ones.

Milk is completely freezable! There is an island I have vacationed on since a child; frozen milk everywhere, never larger than a pint. I'd make up your own.

Playtex has a cooler called the Fridge to Go which holds 2 bottles/sippy cups and keeps them cold for up to 12 hours. I think it's about $20 and can be purchased at Target. I put my 1-year old's milk in there, but for my 3.5 year old I buy the boxes, since he doesn't drink as much milk. I usually 1 or 2 in the diaper bag in case we have to leave the house in a hurry or get delayed some where.