Blur

Checklist:

-Wreck your rival
-Earn 50 points in one motor mash event
-Win a motor mash event

Obviously to wreck your rival your going to want to concentrate all of your attacks on the car with the arrow above it. This can be frustrating if everyone keeps stealing your wreck but it's easy to accomplish.

As for the other two, they are easily accomplished after reaching Rank 30. Equip yourself with the Mod which enables you to fragment mines by driving close to them. Spend all your efforts looking to fragment the mines which are dropped and only directly attack cars if you're not going out of your way to do so. The mines will fragment if you crash into them but you can do without getting wrecked because it will cost you time and give your opponents points. Also power-ups can fragment mines but they can be used in better ways.

This should gain you a ton of points on it's own but you can gain even more..

Once your reach Rank 40 equip the decoy mod which turns all of your dropped power ups into decoys, alongside the fragmenting mines mod. Now do as before but this time every power-up which you pick up, just drop it as a decoy (unless you pick up a mine, in which case you may want to fire it out in front of you and fragment it or headshot an oncoming opponent). Doesn't particularly matter where you drop the decoys because everybody seems to be incredibly reckless in this game mode. Though the best places to drop them are high traffic areas and right behind power-ups.

The only reasons you may not win the match are if others are doing the exact same thing and are more efficient than you at doing it, there simply aren't many mines being dropped or your facing smart opponents (unlikely). The majority of your opponents will likely fall incredibly short. Trust me, using this method I gained a Winning Streak x10 and in my last game on the figure of 8 track I scored 218 points. Hope this helps you out.

To get this you need to,

Win a motor mash event
Wreck your rival
Earn 50 points in one motor mash event

This one can be frustrating to get, i suggest either boosting this or playing quite a few games. To get this by playing always choose a car with lots of health, put offensive mods on and always go after your rival, (has an arrow and glows red on the mini map) Eventually you will wreck your rival if you keep going after him, but if you get wrecked yourself your rival will change to the person who wrecked you. To get the most points go after bolts and mines, try to get all 3 bolts into a car to get bonus points and just drop your mine infront of powerups. This will get you 50 points in no time, and if you wreck your rival chances are you'll have enough points to win as well.

Nowadays apart from the Skirmish Game Mode, the online for this game is dead, so if you want a good chance in getting this achievement, you will likely need to boost it.

To access the Motor Mash Events you will need at least 4 people in order for the game mode's time limit to start ticking down to 0. However as a recommendation I would suggest having around 6 to 8 people just in case some people have connections issues or other problems.
You will need to be at least Level 15 before this game mode will be unlocked. However if someone in a group is Level 15 or over, they can invite anyone in a party or on their friends list to join the lobby, and they will be able to participate even if they are Level 15 or under.

There are 3 requirements you need to do in order to get this achievement, but you can work on all of them at the same time in one match.

Now there are 2 game modes you can work on this achievement. Motor Mash or Team Motor Mash. Among the two I suggest you work on the Motor Mash event. You will all be placed on individual teams and you will be battling against each other. Therefore only 1 player will be able to win 1 match per race.
The boosting method is pretty simple. The person who is going for the requirements simply needs to travel around the track, grab whatever power-ups they can get and use them against everyone else. They will have 3 minutes to complete the requirements. You don't have to do all of them in 1 race, but if you have a large group of players, the possibility of doing all 3 of them is quite high.
The players who are not going for the achievement in the race simply need to meet up at a certain spot on the map and squeeze in, so that they can become easy targets for the person going for the achievement. Your car though may fade out so to prevent this you just need to press or for a quick moment.

Requirement 1: Wreck Your Rival: For the player that is going for the achievement, one of your opponents will have a Red Arrow flashing on them. This will be your rival. To wreck a rival you just need to continuously attack them until all their health is drained and they blow up. Be-aware that if you wreck an opponent in this game mode, you will become their rival as well.
If this doesn't work then the other method is to have 1 player wreck you and you then wreck them back in revenge.

You may get this achievement a the same time if the player you wreck has this viral achievement...



Requirement 2: Earn 50 Points In One Motor Mash Event: This can only be achieved individually. You cannot earn this as a team. Everytime you hit an opponent with a weapon or with your vehicle that drains their health, you will gain points. You get extra points for performing combos, wrecking someone or other features. 50 Points can be done quickly in a Motor Mash Event and this along will gain you more fans towards your XP leveling in the game.

Requirement 3: Win A Motor Mash Event: Pretty simple. Come in first place in the game mode. You should get this the same time as the other 2 Requirements. To win a Motor Mash/Team Motor Mash Event, you or your team need to have the most points among anyone else in the match.

Random Players

If a random player joins whilst a race is going on or in the lobby, the best method is to wait and see if they're going to quit and if more randoms join or the random player is too skilled then everyone needs to back out of the lobby and return to the menu for a few moments. That way they should get the idea that they are not wanted and will not participate.

Another recommendation as well is to set your XBox Live Online Preference to Offline. By doing this the randoms players cannot "Join Your Session In Progress" using the button.

Lastly these game modes are known to be pretty useful to boost towards these 2 achievements...





Once you have completed all 3 of the requirements, this achievement will unlock. Hope this helps.

Good Luck!