Free Play mode to race any of the cars that you own against cars with the same class (Add variety in the grid, e.g Z4 GT3 with AMG GT3, etc), with adjustable difficulty, laps, on any track available. P.S I wouldn't mind paying either R$ or GC for that, it's worth it for the fun that i'd have playing this game.
Add the Brands Hatch GP, Abu Dhabi Yas Marina, Nordschleife (If possible), Road America, Donington Park, Sebring International Raceway, more Formula E tracks plus MORE supercars tracks.
This one will be a bit of a dream, since I play project cars I have always wanted karts in Real Racing 3. I think it'd be fun, plus adding karting tracks. It's highly unlikely they'll even consider this, but it can always be a possibility.
MORE cars in the Motorsports series!! It's so boring to see a grid full of the same car with the same livery. If there's gonna be only one car in a season, at least have it with various liveries. Even two cars gets boring if they don't look different.
Motorsports should be different from career in that it should have a format that is more lifelike, for example: Having a tier per track (One configuration only), have a "practice" session, which could be something like the endurance mode or just a few practice laps before the race, then a "qualifying session" aka time trial for the track, then the race itself (at least a 5-10 lapper). It's motorsports! It has to be different from the career, otherwise we're just gonna end up with a second career and it's just gonna be so boring.
That brings me to this: Qualifying!!, Difficult qualifying, so that we don't end up in pole position always, but it's gotten so boring to always start at the back regardless of skill. I want qualifying, even if it's only for the Free Play mode; I want something similar to Project Car's Solo mode.
Driver customization; You know how all drivers in the game have a white helmet with white overalls? It's boring, I want to be able to put Vinyls on that, or have default designs that you can even see while driving in cockpit mode (E.g. gloves, overalls, helmet).
Last point: REAL SPEED, the cars are way too fast. Maybe that's good on some cars, but I don't like seeing that on Motorsports cars. I want the real speed and a feeling of driving a real car. Kind of what the Mazda RX-3 makes me feel, it makes me feel the speed, the grip, the sliding pretty well. I want to feel this on the GT cars specially, plus if I make a bad mistake I want the car to be able to spin, not just slide a little. Plus if I crash HARD I want the car to not function correctly, or even to not function at all.
Maybe it's too much to ask, or whatever. These are just wishes of mine for a better Real Racing 3.