Does anyone make a car cover that is truly waterproof..????

Title pretty much says it all. My latest purchase failure is a Budge "Rainbarrier" cover that is/was warranted for 10 years against "defects in materials and workmanship". Apparently that doesn't include the waterproofing. It lasted 3 months in the Florida sun before it started leaking. I've since treated it with Starbrite waterproofer, which seems to work in all but the heaviest downpours. So... is there REALLY a waterproof car cover out there, other than a plastic tarp..?? Since my car sits in the driveway and has a leak somewhere in the rear window which I can't seem to find, a waterproof cover would be really nice......