It takes ~35m in exploration data to hit elite, right?
I think it's about 90-100m total.
I'm Ranger right now, on my way back from my longest jaunt yet, I hope it's enough to put me over the top. My total distance traveled on this trip is probably about 100k or so, maybe as far as going to Beagle Point and back, although I didn't make it that far.
I followed our arm of the galaxy counterclockwise, then skirted toward the outer rim until I was about a quarter of the way around the circumference, then decided this was taking far too long, cut in across the middle of the galaxy, hit Sag A*, out the other side, stopped by Jaques Station a few weeks ago, then kept heading out toward the outer arm, and I'm now following that arm back home. I'm less than 20k away now.
I always scan the main star, along with any stars that are close enough to scan without moving too far. Lately, I've been scanning the metallic landable planets that are close to the star for materials, but I don't have to go that far for those. And, of course, I scan all ammonia, water, and earth-like worlds that I come across (found a system just the other day with an earth-like and
three water worlds). And I keep an eye along my course for any one-off stars like white dwarfs, neutron stars, or black holes.
No idea how long it will take to turn all this in. I don't plan to do it all at once, either, since I can use exploration data to level up three different engineers. I should have more than enough to get all three to rank 5, and I'll dump the remainder at either Farseer or my home base at Sol.