Ive had 3 company cars in my life time, and 3 years was the sweet spot in terms of not requiring any major maintenance, 1st one was a Focus ST3, 90k hard miles over 3 years, no work required apart from stone chip correction, 2nd was a Honda Accord Diesel, which just required a DPF, i did a lot of local miles in the last year. Last Company car was a Audi A4, which i had for 4 years, i did 95k miles in that, but in the final year i started to have lots of niggly problems, the power steering rack went on it, it needed a new EGR, the electronic boot motor failed etc etc.
Most of the people in the office, have had more 'luck' with jap and korean cars than the german rep mobiles in terms of maintenance work.