Chevrolet Tahoe 6.5L Diesel
The Tahoe was a completely different type of SUV for GM and introduced the world to the modern comfortable full-size SUV. The Tahoe had a lesser-known counterpart with a V8 engine though. The 6.5L Diesel was considered the worst engine GM had ever put into a vehicle. The 6.5L Diesel was notoriously unreliable (via 6.5 Turbo Garage).
Although the Diesel variations of the Tahoe are among the rarest, it doesn’t necessarily mean they’re worth considering. The two-door Tahoe with the gas engine was a much more reliable car and the price of the gasoline versions of the Tahoe are continuing to rise in value.