Exhaust system affects fuel efficiency. If you notice you have to fill up your gas tank more often than normal, have your exhaust system checked out by a muffler repair shop. Similar to the vibrations, increased fuel use is a sign something is wrong with your car. When the exhaust leaks, your engine works harder.
Temporal summation is the linear addition of graded potentials that overlap in time; that is, a second potential arrives before the first one from that source has finished. Spatial summation occurs when there is simultaneous arrival of graded potentials originating from more than one synaptic input. Summation occurs at the trigger zone. Typically a multipolar neuron has many active synapses at a given time, with multiple potentials being produced at each.
Hollywood court dramas often make the closing argument a brief, terse statement; in real life, it can go on much longer. Summations lasting an hour or more are typical. Depending on the complexity of a case, the entire summation period may last several days, particularly in jury trials where numerous witnesses and difficult Scientific Evidence have been presented.