For this achievement you are required to win 6 races in a row in local multiplayer.
Firstly plug in a second controller
Choose the 'Play' mode from the main menu
Select Belgium (in my opinion the easiest track) and press to customise the race.
Lap Amount - 3 (you can choose to have more if you wish)
Power Ups - None
Damage – Disabled
Modifiers - 'Project Orion' and click to add it (Permanent Boost)
CC – 1,000
The only tip I can give you is to not to take the shortcut after the Factory, take the proper route and use the KERS boost to your full advantage (with Project Orion this will get you max boost!)
Remember also that you can hit restart whilst going for this achievement and your win streak will not reset. (Credit to Blue n Gold Eel)