Keeping straight, Lexi patiently waits for traffic to turn off, passing through the intersection before squeezing the ECUL between the truck and a speeder to the right. It's then that she truly goes into action, as she pushes the throttle forward in an effort to leave the Silver Speeder behind.
Clearly your tail is caught off guard; still, they react in time to give chase, although they are having a considerably more difficult time maneuvering through traffic as they accelerate to keep up. It's not enough, however, and by the time your pursuers have gotten up to speed, they're already falling behind.
There's moderately dense traffic ahead, wheeled vehicles, speeders of all kinds, plodding along at speed limit pace. Weaving in and out, threading your way through vehicular obstacles, things are looking good. Up ahead, you see a large, industrial hover vehicle, moving along with traffic, a symbolic business logo proudly emblazoned on the rear in purple glow light.
Then you see it, a second or two before impact: a rocket of some type, streaming in, coming down at an almost entirely vertical angle suggesting it was launched from high above street level, on the right side. It connects in the front, a direct hit to the pilot's cab, a booming explosion rocking the vehicle. Immediately, the vehicle lists to the right, then severely careens in the same direction as it spins out and crashes into a building, coming to a dead stop. A couple of speeders crash into it from the rear, with collateral collisions piling up behind them. Traffic moving ahead in front of you quickly slams on the brakes, scattering across your side of the street in a chaotic mess.
Cab on fire, the length of the industrial vehicle and the pile-up ahead is blocking your path completely, as a wall of wreckage and stopped vehicles has entirely congested the three lanes on your side of the street.
Your only option to evade your pursuers is to aggressively veer left, and go against oncoming traffic.
Lexi won the Competitive check, increasing separation between you and the Silver Speeder. It was Short Range, it's now Medium (the goal in a Chase, for the pursued, is to get the distance between you and the pursuer beyond Extreme, leaving them hopelessly behind).
Converting the Silver Speeder's Triumph into 3 Advantage, that brings their total to 5 Advantage, which is a fairly large chunk of Advantage, which I've interpreted as the collision above, further complicating your attempt to escape your pursuers.
So, the 3 lanes of traffic that you guys were moving along with/through, has essentially come to a dead stop, and can no longer be traveled. The bottom line is that, if you want to continue to evade your pursuers and try to get away, Lexi is going to have to navigate the ECUL past the wreckage ahead, which will require her to first enter and navigate through the three lanes of oncoming traffic to the left, circumventing the wreckage. After that, on the next turn, assuming success, she can move the ECUL back on to the right side of the street, moving with the traffic going in the same direction.
The alternative is to slam on the brakes and stop with the rest of traffic. To avoid collision, the check for that would: 1 Red, 2 Black.
The ECUL is still at Speed 1. If it stays that way, the difficulty of moving into and through/against oncoming traffic will be: 1 Red, 6 Black.
If Lexi decides to up the speed to 2 (ECUL/typical speeder max), then the difficulty of moving into and through/against oncoming traffic will be: 1 Red, 1 Purple, 6 Black.
If your character adds dice to Lexi's pool, go ahead and roll them yourself. Also, the only Vehicle Action that would be a secret check is 'Scan the Enemy'; all other vehicle actions you can roll the dice yourself, using the RaW.