Molly

Hi everyone, Looking at buying a high mileage automatic S4 2017. It's been advertised at 120,000 miles, advert says it's mainly motorway miles. Says it's recently had new oil and air filter. Advertised at just under £20k but says open to offers. Is there anything I should look out for, and what is the lifespan of this car in terms of miles? What would you think is a good price? Looks in pretty good condition, could do with a wheel refurb. Thanks