Stretching The MilesThe debate between the reliability and longevity of modern cars vs. older cars is a tough one. On one hand, older cars are simpler and more mechanical, with less to go wrong, and with proper maintenance, should last as long as possible. Modern cars, though, are often plagued by technological features or less robust materials used to keep production costs down.Someone has made a compelling argument for modern cars, stretching his current car's mileage into the hundreds of thousands, and what's even more interesting is that the car itself is an early hybrid model.300,000-mile Hyundai IoniqTikToker and YouTuber Taylor Phase posted on his socials about his journey with his Hyundai Ioniq Hybrid. For those who don't know (or forgot), Hyundai first released the Ioniq name as a hybrid nameplate before spinning it off as the EV brand we know today. The post starts with a video caption saying the car has over 300,000 miles (317,935) on the clock but still uses the original transmission, engine, and, shockingly, the same hybrid battery.His video isn't just about his personal car and journey; he also says anyone can get their car to 500,000 miles with the same engine and transmission. This is, of course, provided you follow the tips he covers in his video, which he lists in detail. He first stresses the importance of oil choice; he says AMSOIL is his preferred brand, and he even talks about using variations of the recommended oil viscosity. His car tells him to use 0W-20, but during the hotter months he puts 5W-30 because oil thins out more under extreme heat.Next, Phase says he religiously checks his coolant levels and even pH-tests them with strips. Right now, his car is experiencing an issue where coolant levels are dropping, but he hasn't yet identified the specific cause. His spark plugs get replaced every hundred thousand miles, while he manually changes the brake and clutch fluids; he takes a turkey baster and sucks the fluid out. His last tip to owners is to treat your car gently by not flooring it too much or being too hard on the brakes.Brand GuidelinesIt's easy to discredit Phase's claims if you're a skeptic, but he does seem to have proof that his car has indeed reached the claimed mileage with the original engine and transmission. Luckily, automakers provide service-interval timelines in the owner's manual that we can reference. Phase is on the mark with the oil variations: the owner's manual recommends 0W-20 for better fuel economy, but 5W-30 or higher helps the engine stay lubricated in hotter temperatures.The manual also says spark plugs should be replaced every 97,500 miles, which he's close to with his 100k intervals. Where things get tricky is his claim that the original hybrid starter and generator belt is still in use. Hyundai says that the HSG belt should be replaced every 67,500 miles or 48 months, which means his car is way overdue for an HSG belt replacement.