I can not get challenge 70. When I get close, I don’t have enough moves. Help!?

What worked for me - when there are no more moves left (without hitting something) I moved the 2 vehicles on the top right up. That's the purple and green cars if you're using the race car(?) skin or the if you're using the skin with the buses and cars with the white stripes. That opened it up and solved the problem and I even had 1 move leftover. Just a bit nerve wracking not to hit the people.

Looking at other threads, there was a suggestion to change skins for your background. I swear there were ten less cars when I switched skins. I won it!