Danger Zone

This is more a note about this achievement rather than a full rundown of what to do. I'll give some basic tips though from my experience as well.

First up - You don't need to do the Bonus Phase. You only need the medals for each of the 4 Test Phases. I was curious about the bonus ones, but found that both this Tier 4 popped at the same time.

Besides this, don't worry about your medal rank. The best way to approach each level is to observe the coin pickups. You won't need them to reach the bronze for each level, but they give you a better idea of the path to take. I found the strategy goes like this:

1) Practice Run to see where the pickups are
2) Get the Bronze coins and build the smashbreaker (or pick up ones)
3) Smashbreak to and from the remaining pickups

Usually when doing this, the bronze and silver pickups have an additional smashbreaker next to them to help propel to the next one. Additionally, hitting a car while performing the flips leads to excellent bonus/multipliers. Getting that up in the 10+ range can really start adding huge score boosts in short order.