If you have the room, you might consider putting a carport roof next to your garage, or over your driveway. Agreed, the 4-door sedans are rising in value, but so are the other body styles. The most recent value guide I have (published by Cars & Parts Magazine) is from 1997; it states that the 1964 Valiant 100 4-door sedan is worth $5400 in #1 condition, $3800 for #2, and $2200 for #3. The 200 values are $5700, $3900 and $2300 respectively. Their #1 condition is concours, #2 is show, and #3 is show/street. The hardtops and convertibles are worth much more; even the station wagon has a higher value. Values were almost unchanged from the 1963 through 1966 model years. This is more than 15 years old. Online today, a few convertibles are asking $16,000 to $18,000 and hardtops just about that much. The priciest sedan was over $8000 in Illinois, but it claimed box-1 miles. Yours seems to be closing in on 300K, but so long as it's well-maintained, it should outlast all of us.