If it's too hot for kids or pets to be in a car, it's too hot for wine.
A simple fix is to bring a cooler with ice in it. Deposit your purchases in said receptacle and rest easy knowing your lovely juice is safe from the heat.
There's nothing worse than tasting a delicious wine in the tasting room and getting a bottle home only to have it taste different, or in this case, worse. Leaving wine in a hot car will cook it. It won't take long.
There is a Conoco station less than 5 minutes away from our tasting room. They've got styrofoam coolers and ice for purchase in the event that you've forgotten your own. It's a small investment that will keep your wine happy and cool during your wine tasting shenanigans.