I have the GP40 as well and recommend it to anyone wanting peace of mind when you have an older battery. Definitely saved me a few times when I was on the last legs on my original car battery. I have a 2.4L 4-cyl and had 3 cranks on it and was still sitting on the 50% charged. It also holds it’s charge for a long time too. I try to charge it up once every 3-4 months.