I have a 2011 Clubman non-turbo and I averaged about 32 mpg. I decided to try a performance chip from Thorton Performance that cost less than $100.Thorton sells 3 stages and I purchased the 3ard stage that boosts power by 60 horses!
I was skeptical but said what to heck and I received it and plugged it in the OB port and off I went. I've had it in for 3 months and it does what it claims The power gain is apparent and fuel ecomny has improved. Thorton claims 60 horsepower
jump and said I'd see 5 percent improvement in gas mileage and this is in writing. I went from 31 mpg to 39.4 mpg despite driving the vehicle more aggressively. The company has great customer support.Best money I ever spent on a performance bit.