Asphalt 8: Airborne is an amazing racing game for Android devices. I regularly run my battery from full to empty playing it. It is not what one could call a realistic game, what with surviving 200-foot drops and being able steer while in mid-air, but it is fun. And frustrating. The game decides sometimes that you belong in 3rd place. Or last place. Or first place. It is not up to your skill. The game has spoken. But over the longer term, these tend to balance out.
How the game works is, there are a vast number of cars available. Each one has its own characteristics, and you can buy upgrades to them. You win credits for winning races and performing tricks (like barrel rolls and knocking other cars down). There are races against computer-controlled cars, and multiplayer races, where you are pitted against other people online. Kind of amazing what they can do with mobile apps these days.
Each car has a rating according to its characteristics and how much you've upgraded it. You might think that equally-rated cars would tend to perform about equally, but that is not true. There are cars that are simply better for multiplayer racing. Also, I've found that (counterintuitively), the more you upgrade a car, the less well it does against similar rated cars.
The best cars for multiplayer are: Survolt, Felino cB7, and Biome. If you pay attention to who wins races, it's very often one of these. Don't bother with the Corvette or Countache, they just lose. Some others like the Pagani Zonda are fun to drive, and they at least have a chance of doing well in a race, but for dependable top-3 finishes, pick a Survolt, Felino, or Biome, preferably not fully upgraded. Get one and start winning races. That's how you make money.
There will always be more cars and upgrades than you can afford. It takes a lot of racing to win money, but there are a few shortcuts. First, winning streaks: if you place top-3 for 7 races in a row, you will sometimes win a class-D engine upgrade. Be aware of what your most expensive upgrade available is. When you win the upgrade, that can save you a lot. Similarly, if you continue on to get 9 in a row, you can (sometimes) get a class-C. Again, they can be worth a lot of money.
A relatively recent development, the Mastery series of races, also has a few upgrades scattered among the prizes. You don't have to claim them immediately upon winning them. You can look through your inventory and see where it would best be applied.
Another way to save a few bucks is to watch for cars to go on sale. They can be anywhere from 20-50% off.
There's also a bonus for your first race of the day, if you play every day. Double your money. Try to do a race that promises a good payout: one where there are stars to be won. If the race isn't going your way, you can quit the race and re-start, and you'll still have the bonus waiting for you.
There are always "special events" going on, too. These are time-limited, running for 1 to 5 days, and your participation is also limited by "fuel bars" that you have that recharge over time. The money payoffs are fair, but the non-money prizes are what usually make them worthwhile. In addition to earning prizes for scoring 1st place or beating a time, there's a hierarchy of prizes for the top scorers overall. In a multiplayer cup, that means playing again and again, which is usually not worth it. But in a non-multiplayer event, you just need to manage your best race.
Another aspect of the game is "Pro Kits". These are upgrades that can take you beyond the maximum normal upgrades, but in addition to money, you have to have cards specific to the upgrade. Those cards are often prizes in the special events. Although the intent is for the pro kits to be applied after you've maxed a car's upgrades, you can apply them at any time. This is good if your stash has gotten too full for you to open more boxes of cards. However, you need to be judicious about your card use, because you will run out of cards for particular upgrades. So focus on upgrading one or two cars in each class, rather than just applying upgrades all over the place.
Got tips? Tell me in the comments.