If you seriously want to get someone with a car bomb today you wouldn’t do that.
Too many people use a remote starter.
You would use timing device that detonates the bomb a given time after the car is started.
Or as others have said on this thread you use a burner cell phone.
Either way ignition detonated bombs require access to the car for a significant amount of time. That raises the chance of being caught. Better to have a self-contained bomb that just requires attaching the device to the car.
The cell phone detonation also gives the bomber more control of when and where the bomb goes off. If the bomber wanted to kill the governor’s daughter with the boyfriend, they could have decided not to set off the bomb until they observed her in the car with the boyfriend.
Also, reports that the driver of the truck was still alive and that a good Samaritan tried to free him. Seems unlikely in a missile strike that the driver would survive the initial impact - unless it was a bad targeting job.