Fuel injected engines do not experience this problem as much as others do due to fact that fuel remains inside injectors by being under a very high pressure. This way, fuel injected engines would not become so easily obtruded by vapors as other engines would and therefore car would not have same problems to start as another would.

Also, engines might become hard to start while being hot if it coincides with season in which refiners change from a fuel blend to another. Sometimes gasoline refiners change from a higher volatility fuel to a lower one when summer approaches due to way in which hot weather causes fuel to evaporate easier. If refiners change back to a higher volatility fuel while engine is still exposed to days of high temperatures, this could cause fuel to evaporate too much creating too much vapor and therefore obtruding engine.

Besides engine, car batteries might experience problems while being in cold weathers as well and this could affect engine. Batteries function through chemical reactions which loose agility while being cold and therefore, in such circumstances, batteries don't function properly. When this happens, car energy becomes affected and this causes problems for engine start.

If these three problems happen together, starting an engine might become a really hard task to achieve. In order to overcome lack of gasoline evaporation problem, you can spray ether into engine which would evaporate quickly and help engine start. Besides this, you can also to prevent having oil too thick which wouldn't circulate properly by using thin synthetic oils. You should also try to maintain car isolated from cold as much as possible, but by using two last mentioned methods you would experience much less problems at time of staring car in cold weather.