I've had the 6 pound lithium in my 2008 G37S coupe for 5 years now and put 95k miles on it during that time, still going strong. Have one in my 280Z with LS6 for 3 years, all good and I know Phantom (Bill Davis) has one in his LS1 powered 280Z for several years, as well. Many 510s & Z cars (S30 up to Z34) are running them. As is the case with any vehicle that isn't driven at least a few times a week, you want to keep a charger on it to keep the parasitic draw from discharging the battery and "cycling" it because ALL batteries will last longer if kept at or near 100% state of charge, so regular driving or kept on a charger are the best solutions if there is a draw. The other benefit with a Braille lithium is they don't self-discharge like lead, so if disconnected at the terminals or via a disconnect switch (like most race cars), the battery can sit for a year or two and still be at 80-90% state of charge, where a lead battery will be dead by then. The right size/model and proper maintenance is key to long life, but where a smaller AGM battery will average 3 years (more depending on several factors), a lithium battery will last 10-15 years. Other factors are goals & budget (size, weight savings, more power, longer lasting, better performing, etc.) as to which AGM or lithium battery is best for a given vehicle and how it is used.