35 MPG is within the lower ball park typical performance envelope.
Typical mixed local defensive driving achieves nominal 45-49 MPG in my stock 1998 1300cc K11.
Too many variables to make statistically valid comparisons of nominal & real life values of MPG & or KM/litre.
Frequent winter time cold start-ups, mostly short journeys across town, driving style, tyres type/pressures/tracking/fuel grade/ brakes binding & vehicle condition make disproportionately large differences rendering direct comparison indeterminate. Wide wheels (fatties) add weight increase rolling resistance, plus performance mods waste energy & fuel.
I have achieved 63 MPG on a 325 mile summer time round trip driving at steady grand granny 50 MPH on M-way & A roads using cheap supermarket UL fuel. Thats good enough for me. 
Reference; https://www.micra.org.uk/threads/1-3-k11-mpg.59723/
