srj,jr here.... as a person in the "battery business"... well, lets just say i can't really reccommend the use of a yellow top optima for a "car battery"... don't get me wrong, its a good battery, but its a deep cycle battery.  Each type of battery has its purpose, and the use of a deep cycle battery as an automotive battery would really end up being a waste of money... deep cycle batteries are made to be drawn off from, then recharged(hence the name, deep cycle, being "deeply" discharged, and then recharged again)... the lead plates inside a deep cycle battery are thicker and are specifically made to be discharged 50% or more and then be revived... while a car(automotive) battery is a "shallow" cycle, made to be drawn off for a moment and then charged.  A car battery has thinner plates, and with that it has the ability to have more plates in a given area than a deep cycle, giving it more cranking amps ability.  The main problem for a deep cycle battery in an automotive application is that the charging system is basically always charging(normally an alternator is putting out 13-14.5 volts, and the regulator adjusts the amperage, but its never at 0, sooo there is always some amount of amperage going back to the battery) the battery, and a deep cycle cannot take continous charging.  We've seen several yellow top optimas turned in for warranty(blue tops too, they are marine deep cycle)  that are just victims of overcharging(the electrolyte within the battery boils off, even though Optima's are a sealed battery and do not 'gas' like normal batteries, they can be overcharged, infact the only "true" way for use to tell if an Optima is overcharged is to put them on a scale and compare with a new one, have had some nearly 2-3 lbs lighter, from being 'boiled dry')... in normal conditions for a vehicle... in which we get some kinda ticked off folks because we wouldn't warranty the battery(nearly a $200 item) because of "mis-application".... of course the red top is the proper application for a vehicle... best bet for anyone not going to use there car(be it a vette or other) for a long period of time,  is to just disconnect it, or use a battery tender type device for a week at a time out of a month or two... a fully charged battery un-connected to anything can sit for approx 4-6 months at a time before needing a 'recharge' to be considered 'fully charged'... hth

Thanx SJR JR (hth), much for your expertise on batteries. That is interesting and very helpful.