I figured out the Level 5 mission w/ the garbage. The easy part is following the truck to get the first 5 items. In the second part, the 25 items are divided into 4 main groups: monorail, escalator, roof, and firetruck.
The truck will lead you to the first group which is the monorail. Don't start there. Keep driving and turn left so you see the escalator. Then turn right followed by an immediate left. You'll be in an alley -- park the car on the dock. Go to the roof using the air vents, then jump down.
Back up the car until you see an alley to your right -- there will be 2 items there. At the end of the alley, make a left. Go up the firetruck ladder, but don't use a lot of acceleration. You'll have to turn around to get two more items on the sidewalk next to the firetruck.
Follow the street which will turn right. the escalator should be straight ahead. Get the 4 items in the center before going up the escalator. Follow the street, and as it turns right, park the car near the stairs. It doesn't matter which side of the road.
There are two items on the one side and two on the other. Use the lamp on the far end to jump to the monorail track, then the edge of the track to get to the other side. If you can't see the last item, check your map. It's hidden behind the railing.
Once you have all 25 items, jump down to your car and head back the way you came while following the truck. On the freeway, take the first right -- yes, go through the barricade. Follow the detour sign then go straight ahead to the DMV.