There are 31 cups and 27 events. You need to win every cup to get gold. If you are tied for the lead, it will count as a win. You can retry a race as many times as you want, so there is no reason why you can't get this achievement with a bit of time. Make sure to upgrade your cars, everything except for the body upgrades. They will make you slower. In the races, avoiding others is key. If you go off track, press to quickly get back in the action. Braking should be reserved for only the tightest of corners. For the others, a short release of the accelerator, then turning and reapplying the accelerator will see you in good stead.
The events are a mixture of time trials, derbies and bonus races. For the time trials, leave them until you have the fastest car available in that class. It will make them a hundred times easier. Refer to Keep on Truckin' for Derby tips. The bonus races are not too difficult. Some have you simply driving around an oval, Nascar style, with regenerating nitro.