Andrew
That depends on engine wear. engines can last two races, so the allocation of 20 for the two car team should be enough, unless you're doing a lot of quick races in between the league races.
Yes Andrew. Engines
can last 2 races. But, fresh engines are faster than engines that are 1 race old. A study a friend and I did a while ago showed that, depending on the track, a 1 race old engine can be as little as 0.1 seconds slower to as much as 0.7 seconds slower. If you use a fresh engine every other race while a competitor is using a fresh one every race, it'll be hard for you to compete with them regularly.
Also, while you can get engines through daily rewards, only 1 day guarantees that you will get an engine. You can get an engine from the A, B,or C option, but there are 4 other rewards that can show up for those 3 options.