2005 Hyundai Santa Fe "05 focus exhaust leak smell" Questions

...05 plate 2 litre Focus Diesel. Engine runs seemingly happily, no odd noises, no visible warning lights or messages. I expect that you have an oil leak that is dripping/running on to the exhaust. The ...

...05 ford focus zx4 used at quarter tank of gas in 21.1 miles. what could be causing this? should be an odor of leaking gas somewhere, and/or a stain on the ground where it is usually parked. have ...