How do I get rid of ctOS scans?

I'm having lots of issues with ctOS scans in Watch underscore Dogs. I'm driving a fast car, but the scan areas are huge. If I use a jammer, it just spawns new scans that follow me in the direction I'm moving. If I switch direction, I'm caught in the existing scan. Whenever I seem to be in the clear, new scans just spawn around me and close in on me until I'm caught in a scan again. Hiding in the car doesn't help and I've already tried using all my jammers (about 10, crafting on-the-fly), chaining them properly.

How can I get rid of the scans for good?

Apart from jammers there isn't much you can do to stop the scans. As you may have already noticed there is a small indicator telling you the progress of the search right under the minimap. If this bar reaches 100% the police has located you and you have to get out of the search area ASAP. The bar goes up whenever you are in an active scan (jammers can interrupt this) and it will slowly reduce its % as soon as you leave a scan area. Once it reaches 0% the scans will stop (there are some exceptions). Sometimes escaping the police can be easier than escaping the scans (you can perform takedowns on cars while the scan is an "invisible" enemy) but then again there are some missions where the scans will just restart.

For escaping the scans The most important thing isn't really speed but vehicle handling. With the fastest car ingame you could technically outrun a scan but usually they just place another one right in front of you as soon as you leave the previous scan area. What really is key is maneuvering the car fast. Make sure you take a road where you can cut alot of curves. Usually there won't be more than 3 scans active at once and if you zigzag you shouldn't have too many troubles escaping all of them. If you really have to run through one (let's say there's a scan right on top of your mission destination) you can still use your jammers.