This will be old hat to the old timers here, but hope it is an encouragement to some of the newer members. I have been racing for about a year and joined MRR about 6 months ago. I am now at level 315 and have raced over 1300 hours.
1. Learned to force close at the end of races to save the agents. This keeps me playing without waiting for repairs and I get double fame points for nearly every race (provided I win). Force close immediately after fame points are awarded. If you don't get first place, force close before the race ends or as you cross the finish line, but must be before your finishing position shows on the screen. In this case, the race really didn't happen at all. And yes this works even if you are leveling up but if that is the case you waiti until you are given the notice that you have reached a new level. Then nearly simultaneously press the "continue" button AND force closs the app by double clicking the home button (this assumes you are on an iPad). Obviously you have to touch the continue button a split second before closing the app.
2. Dumbing down the bots. In several series there seemed to be one race I could not win without spending way more GC for car upgrades than I would be rewarded with for 100% completion. This was usually a drag race or speed snap. The "art" of slowing down the bots requires losing the race repeatedly by a wide margin. Eventually this will slow the bots so you can then win. This means you cannot force close at the end of a race, you must let the entire race statistics appear on th screen, so bye bye to your agents. So it is very handy if you have a car you are able to sacrifice while getting beat badly, saving you fast and fully serviced car to race after the bots have been slowed. Of course, that is not always possible if you are limited to one specific car for a race. So you just have to pay the 1 GC to buy the services of the agents have you have finally won the race. If you are fortunate, the agents will be available for free.
3. "Renting Upgrades". Never would have thought of this quirk without MRR, never ever cloud saved my game status, but this is a wonderful tool that lets you be competitive in time trials. The process is to clould save you game and then buy the needed upgrades and run the time trials with a fully upgraded car. Your time trial times will be recorded and NOT lost when you restore your game back from the cloud. Of course you still need a lot of GC on hand to do all the upgrades on the extremely expensive cars. Just remember to restore your game from the cloud to get your GC back.
4. Participate in events. This was something I was not doing, I was totally focused on completing series, buying cars, and leveling up. But the events add new excitement to the game.
5. Turn off traction control. After hundreds of hours running with TC on it is hard to change your habits and the track. Have patience, racing with TC off will eventually improve your times. Do not go cold turkey are you may get totally frustrated, start by turning off TC when you race a particular racetrack. I have a long way to go on this one
Anyone wanting more detail on these can post your question and many many people can help.
Okay, that is my top 5, I certainly have learned many more tips/tricks that are to numerous too mention. This place is a treasure trove of helpful information. Thanks to all of you.
PS, wish I could get Kotter reruns, but either the device, the connection speed, or the IOS8 version seem to block my reception.