Bring the heat up as much as possible before you paint, (have all your prep. done) kill the heat, paint, as soon as the fumes are gone turn the heaters back on. If it's really cold you won't be able to paint the entire car that way, it will require stages. You will need a faster/hotter thinner for cold weather. Ask the sales rep.
Safety first guys, I know of one guy who blew himself up by not using a good safety light, he bumped it, it broke and the fumes ignited...