Need for Speed: Shift 2: Unleashed

have to be in career but you can drive the same race every time

active hard in options and press [START] (not B)

you can do it "legit" or drive 75x the same race

the fastes is "Poster 3" - DRIFT - Irwindale Wheels on Fire - the first
i used the classic DODGE CHARGER R/T (no tuning), very easy to beat the 110 points
after the races you can use B to play again - shorter reload times

To add to DeaconFrost2k solution, I found the second race at Toyota Speedway at Irwindale to be much, much easier to beat the 153 score. It is a 2 lap oval, takes a bit longer than the first one but it is twice as easier.
I am using the Team Need For Speed Mazda RX-7 (FC3S) for it.

Win 75 offline career events on hard difficulty, every race is an event, some are series of events, this will pop mid series at the end of a race or event if you have fullfilled the criteria. The lesser achievements 25 wins on easy and 50 wins on medium also stack with this one so you will get them whilst progressing to this one.

Doing it legit is not as hard as you may think and will save wasting a good hour or two tediously drifting the same track time after time when you can get it during standard gameplay progression.

Winning modern D is easy because you pick a decent car like the lotus elise and will easily thrash the AI even on hard without any upgrades. Basic rule of thumb is get ahead by first couple of bends and race clean and steady to stay ahead.

Moving on to Modern C pick a decent car like the audi R8, upgrade it but dont take it outside of group C, this common rule is key to ensuring the grid stays less competetive and so easier to beat. The same applies to retro and muscle and modern B selecting a decent car upgrading it staying just inside the cars original class.

Winning virtually all drift events on hard is very easy even with the basic courtesy drift alliance nissan or using the awarded need for speed mustang, using a better drift car and tuned setup will greatly simplify winning all drift events on hard. Recomended experienced handling with disabled traction control in gameplay options.

Dont bother exerting yourself to win events that supply the car like hot laps, eliminator and time attack will probably also prove more futile to try to get 1st place, there are ample events in Modern D,C,B drift, retro and muscle to attain this achievement with relative ease so you should also have this before group A which is where it also all becomes much harder thanks mainly to the appauling steering and AI that seems to have uncanny abilites of speed, cornering, racing off track without penalty, will also ram and side swipe without reason or cause or just as bad leave dead AI cars strewn in extremely awkward locations so I very much recomend going for this achievement from the begining, you can always turn down the skill level afterwards if needed for the later faster groups.

Some of the cars I used remembering dont upgrade beyond their original group, concentrate on speed and acceleration but leave room for others to aid handling:
Modern C:
Audi R8 (engine swap) + other minor upgrades Group C
Retro:
Mercedes 190E euro Group C
Muscle:
Shelby 427 classic muscle Group B
Corvette stingray classic muscle Group B
Dodge Challenger Concept modern muscle Group B
Modern B
Lambourgini Reventon Group B

You will feel much better getting it this way giving you an opportunity to get a better feel for the way it handles and it will give you a better sense of game value as I personally have a very low opinion of this game, in may respects its predecessor was much better and without doubt far less buggy.