Car: Fix, or don't fix (and trade it in)

My girlfriend recently scraped her car against a pole in the parking lot, causing major paint scrapes and a dent in the left rear quarter panel that will cost around $400 to repair. The car in question is an '03 Pontiac Sunfire with ~60K miles on it.

The debate is whether it to repair the damage or not.

She has been considering replacing the car, either selling it privately, or trading it in for something else. I suspect at best, she'll get about $6K for it. If she was selling privately, it would be a no-brainer to repair the car.

What I'm wondering about is: would the damage described impact the trade-in value? It might well be that the difference between trade-in value and private sale value is not that large once the repair cost is factored in. The value of being able to do a trade-in deal without having to deal with the hassle of a private sale is higher than it might otherwise be, because of an extreme shortage of spare time to deal with car hassles.

I'm suspect the most economic decision is 'fix it', I'm interested in hearing "WWMD", especially those of you who are familiar with the auto trade.

Fix it. If you don't, you're giving them leverage to give you less money on the trade.

Coming from a previous car saleman, you should fix it. The dealer will use any excuse they can to give you the lowest amount possible for your trade-in. Even if your car is flawless they will use the lowest blue book/edmunds value for the car, usually either fair or poor, never the perfect/excellent ratings.

Whether you decide to fix it or not, never take the dealers first offer on a trade-in. Most people will work forever to negotiate the price of their new vehicle with the salesman, but then they'll take the first offer they receive for their trade-in. You can almost always get them to give you an additional $500-$1000 for your trade-in with minimal negotiations, especially if you've already agreed on a price for your new vehicle. Dealerships hate negotiating with a customer for 2 hours on the price of a car only to have them walk out because they're not happy with the trade-in value on their old vehicle.