Need for Speed Unbound

First, do consider getting most of the collectibles and 3 stars online if you can because your progress shares between online and offline, but you can only get the reward credit once (edited).
You can check your progress from the challenges tab from the map. You can also check progress by viewing a specific collectible or activity you're missing district by district. However some district only have one certain type of activity or collectible and can be easily overlooked.
Smash the collectible first so you can have money to fully upgrade your online garage for later activity runs.

Collectibles
There are three kinds of collectibles in total.
80 street art, 100 bears, 80 billboards. Street art needs you to stop and press X, Bears and billboards need to be smashed to collect. There's always a ramp nearby for billboards that are hard to reach. All of them are acquirable with a maxed-out B car, so just do them in your free online mode cars(BNR32, GTI, G) if you can.
Activities
There are four kinds of activities in total.
135 stars for long jumps, 150 stars for speed traps, 105 stars for drift zones, 90 stars for speed runs. There's a lot less traffic online and no cop cars during the day compared to offline, adding another reason to do them online. Remember you only need 3 stars and do not need to beat the rival if you find one activity annoyingly hard. I recommend you progress through the story first to get some free cars we need for 3 starring online.(The cars you won for free in offline can be used online, too. The ones you need to look for are the night races on Thursday and Friday. If you got the buy-ins for the car and the Saturday race as well as the car needed for the big race, you can progress through the story faster by getting arrested on purpose with no money on you.)
For speed traps and speed runs you need a car that's relatively fast and as grippy as possible. The car I recommend is ASAP Rocky's Merc 190e. It's free, has a high top speed and can be obtained by progressing the story mode to Week 4, by winning the head to head against him. You need additional credits to purchase the grip tires and elite differential. Once you've done that go the the handling tab from garage or by pressing in game and move the first slider to as left as possible, the second all the way to the right. Now you've tuned the right vehicle and it's time to get stars.
Speed traps are relatively easy to three star with our car. In speed runs you need to enter the zone as fast as you can, avoid traffic and get a decent average speed. If the car understeers in the corner, lift up your throttle until the car gets in the direction you need. If the car oversteers, counter steer and if possible use burst nitrous to get the car straight. Do not use more than 1 bar of burst nitrous in corners unless your car oversteers.
For jumps and drifts, the car you need will be the Dodge Charger Hellcat, which can also be won for free offline. First, you need to upgrade all the engine parts to the maximum except for the supercharger and buy the elite diff. You also need off-road tires and off-road suspension for jumps, drift tires and neutral suspension for drifting. Do not buy the road suspension or tire.
With off-road tire, tune the first handling bar to as left as you can, you can leave the other two. Your Hellcat should do 3 stars on most jumps without issue with a running start. For some jumps you found trouble that are not off-road you can always bring the Merc we built for speed traps and speed runs.
For drift zones, with drift tires on, tune all three handling bars all the way to the right and you are good to go. With this tune, your car should be able to drift in straight lines even if it does not look like it's drifting. In the drift zones, brake to drift in the corners, and keep steering left and right in the straight-line if you have plenty of time on the clock. In the U-turns, use handbrake(X) to drift and use burst nitrous you get from drifting to exit the corner. Once you've reached 3 stars or beaten the rival, get to the finish as fast as you can as if you were playing speed runs since drift zones are time limited.
With all the collectibles and activities completed, you should get another few free cars for both online and offline mode. The 600LT is a very competitive car for online S races and the Aventador S Roadster is one of the cheapest cars you can get to S+400 in the game.

Update March 2023: Online Cop cars and a new activity called 'Hot Lap' are now added as a part of the 'Vol 2' update. There are more cop cars roaming online and their number is based on how many players are being pursued and their heat levels in your session, but if you don't hit them, they will never come after you. In a 1-player session, the number of police cars is basically the same as offline. It is still the recommended mode to do all your collectibles and activities online as your heat dies down once the cop chase ends and does not carry over sessions or affect your current session as in the offline mode.
The new Hot Lap activities does not count towards this achievement after the update according to the comments.

I did three achievements in one car: Nissan Skyline GT-R R34 V-Spec (1999) and using this map:
https://nfspolska.pl/maps/need-for-speed-unbound-lakesh....69





Nissan tuning:
Engine: PRO 304 HP 3.8l V6
Engine parts all Elite
Suspension Elite (not road or offroad)
Brakes Elite
Tires Elite Race
Clutch and Differential system Elite
Gearbox Super 7-gears

Handling tuning:
20% Grip
Steering sensitivity Central
Downforce +1
Traction Control ON
Drift Brakes only

With any car collect:
https://nfspolska.pl/maps/need-for-speed-unbound-lakesh....0





Okay, so I used three things for this achievement.

1. Walkthrough written by N30YRD.
2. Nissan Silvia (S15) Spec.R Aero (2002)
3. And this map https://nfspolska.pl/maps/need-for-speed-unbound-lakesh....0

Tuning I used:
Base engine 247 hp 2.0L I4
Every engine part is elite
Elite road suspension
Elite drift tires
Brakes and drivetrain parts elite

Handling tuning:
All three bars to the right
Traction control disabled
Drift only with the brake on

This way I was able to complete all drift zones with three stars for a maximum of three attempts. There is no need to beat the score given in the trials, you just need to earn three stars.

Do this in multiplayer just buy the BMW M3 GTR 2005 for £210k give it performance upgrades this is the only car you need to get 3 star on everything this car is a BEAST just as it was in Most Wanted ;) i did almost everything first try

When you are doing the drift zones just switch the tires to “Drift Tires” and you should be good, also for the Seba Skies Ski Jump on the far left of the map be sure to do a burnout on top of the ramp before letting loose down the middle using NOS. You won’t make it otherwise ( hold LT and RT while tapping A)

You can earn the money to buy and upgrade the car by doing the playlist achievements since you get 40k per win much quicker than grinding the single player and you won’t have to deal with the cops being so aggressive!

Short and simple guide easy achievement since you only need 3 stars and don’t need to beat the rival and the “Hot Lap” activity isn’t needed for this achievement