tl;dr: It depends on what you’re trying to do. You can make it less bad fairly easily but a perfect fix is not a DIY job.
If you’d like a perfect fix, you should talk to a professional.
If you’re in a position like me, you might be looking for a solution that looks less bad rather than setting your hopes on a perfect fix. An older car might not seem like a place where you want to spend an amount of money that might be a significant percentage of its current resale value. There’s no reason to have to look at dents and blemishes that make you sad, though.
For a dent like that (assuming a target of less bad again), you’re actually in a decent position. That looks like a fist sized dent near the edge of the fender. If I was working on something like this (and I have), I would (and did ;-) assemble the following:
- Rubber mallet
- Wooden spoon
- A variety of wooden blocks of different lengths and widths
The plan is to push that indentation back a bit at a time, eyeball the result and repeat but stopping before you think you’ve finished the job. Stopping a hair early will reduce the chance that you’ll make a newly convex bump or crease. That’s just crazy making.
The steps are straightforward:
- Jack up that corner of the car so the wheel is less in the way.
- Loosen the fender well liner.
- Reach up with the back of the wooden spoon (or similar) and see if you can carefully press the dent out a bit using only finger strength.
- Check your work and repeat if you see progress, stopping before it’s “done.”
- If the spoon isn’t doing it’s magic, try lining up one of your wooden blocks, tapping lightly with the rubber mallet. The combination of wood and rubber will reduce (but not eliminate) the chance that you’ll make a new crease. Slow, careful work is your friend here.
In short, less bad is totally achievable. If you’re trying to get back to perfect / new, you’ll need a professional’s help.