Test Drive Unlimited

It's almost easiest achievement, you even don't need another player cause you can do it with BOTS.

To initiate Instant Challenge drive close to another car and flash lights by pressing A.

Just turn off conecting to game network in online options and instead of real players bots will appear on map.
I don't have to add that they're quite easy to beat and are driving in unupgraded cars. For raising your chance you can pick car higher class then your "victim" have :-).

Instant challenges are activated when you drive up to another player and press A, which flashes your headlights and initiates and instant challenge.

These are basically races in which you or the other player (depending on who initiated the instant challenge) decides the layout of the course.

Simply win 5 of these (doesn't need to be consecutively) and the achievement is yours.

TIP: Know the limitations of the car you're driving. Don't challenge people who are driving cars several classes above yours. For example, if you're driving an Audi TT, don't challenge somebody driving a Ferrari Enzo.

To beat any car, simply make the finish on the other side of the road across the median. The AL won't cross over grass/dirt or anything except pavement. My races started out at 1.6 miles and when I cross over the median and drove into oncoming traffic, it was .4 miles. My class E beat a class A by almost a mile. Simple achievement, any questions just comment and PM me