Q7s from this era were primarily V6 TDi engines in 218PS and 272PS variants. SQ7 used V8 diesel. Think there was also 2.0TFSI model, but relatively rare and given it's thirst to shift the best part of 2 tonnes, it wouldn't be economical. Some also use plug in battery (E-tron), potentially gives you additional 30 miles. I know that can cause a bit of grief if it goes wrong. All paired with Tiptronic 8-speed boxes. Like everything, the diesel models are all chain drive, and servicing is crucial. That means oil changes every 8-10k miles or less if previous owner was particularly fastidious. V6 engine is a solid workhorse. I've never driven one, but have the 272PS engine in my A4 Allroad and would be the one I would choose. 600Nm of torque and will return 50mpg if driven sensibly, less in a Q7 though I'd expect the Q7 to go through tyres and brakes, so factor that in. Can also pull impressive 2800kg if there's a towbar. These engines don't tend to use oil. However as it's diesel, Euro 6, then you are into AdBlue, DPF, EGR, cats, etc. Better to have a car that's done regular annual mileage. These engines don't like short runs, or you're into emission territory and potential carbon build up. Suspension - standard multi-link or adaptive air suspension from what I understand. 100k plus mileage, you're likely into replacing bushes if not already done.