Start career mode and select this programme during practice 1, 2 or 3 of any race (it's available from round 1 Australia). Can be completed in 1 lap rather than 3 if you perform well enough.
Lift and coast explained:https://www.pitpass.com/54081/Lift-and-coast-explained
Using manual gears I found short shifting helped a lot:
"Short shifting is a driving technique in which the gear is changed up before reaching maximum engine rpm or, more precisely, the acceleration optimized rpm shift-point."
Simply finish the session (you can run down the timer or retire from session) and achievo will pop as you progress through the menus.