Volvo 240A boxy Swedish classic that isn't to everyone's tastes, the Volvo 240 has a hard-earned reputation for being tough. There are still plenty of examples around the used market, making finding one in clean condition a less arduous task than for rarer classics. Plus, when things do go wrong, repairing them is usually a straightforward task. Like any car of its age, rust is one of the most common issues with old 240s, and even an otherwise reliable example can be crippled by too much of it. Wiring is also cited by owners as a common failure point, although many older, cleaner examples of the car will have had historic wiring issues corrected by now.The 240 was designed to withstand the harsh conditions of the Swedish winter, and was designed from the outset to be a high-mileage car — the six-figure odometer wasn't just for show. With the correct maintenance, old Volvo engines tend to be bulletproof, and should require little more than regular servicing to keep them running even after several decades of hard use. The car's reputation has meant that some owners skimp on maintenance in the belief that their cars are indestructible, so not every example on the used market today will be quite as reliable as the average collector car. However, even more pristine examples remain reasonably priced, keeping them within reach of most enthusiasts.Chevrolet Impala SSOriginally conceived as a way to inject some life into the sales figures of GM's B-Body platform, the Impala SS has now aged into modern classic status but remains both affordable and easy to find used. Under the hood sits an LT1 V8 engine which also appeared in various other GM models of the era. This makes parts relatively painless to find if something does break, but it shouldn't — owners report racking up several hundred thousand miles with no repairs needed.However, the Opti-spark distributor is a known weak spot. Like any older car, rust can be a costly issue too, although this will vary significantly depending on where the car has lived most of its life. Since many surviving higher mileage examples of the Impala SS will have led a rough life, lower mileage examples are preferable for keeping maintenance and repair costs to a minimum. That said, even jankier examples can be fixed up into reliable runners without breaking the bank — assuming you've got the skills to do the tinkering yourself.Checker MarathonChecker is mostly known as a taxi manufacturer, with its cabs a common sight across U.S. cities across the latter half of the 20th century. However, it also sold cars to individual buyers under the Marathon nameplate. These cars were, just like their commercial counterparts, built to be simple, tough, and reliable at the expense of all else. They were primitive for their era and never sold in large numbers, but over 60 years since they were first introduced, the remaining Marathons on the road offer a unique old-school charm. Plus, they're no less tough than when they left the factory.Parts are not so easy to find when things do go wrong, but find a clean example and it's unlikely that much will need repairing. Plus, Checkers share parts with certain other cars of the same vintage, and some parts are designed to be interchangeable, like the front and rear bumpers. Earlier cars are reportedly the toughest, with '70s cars declining slightly in quality, but the simple nature of the Marathon means that there isn't a huge amount that can go wrong assuming the car has been properly maintained.