I'm helping out my pension by working as a Driving Instructor and fuel is an ever worrying and increasing cost!
I have two cars - a 2002 VW Golf SDI 1.9L Diesel which I use for teaching manual gears.
I also have a little automatic 2003 Perodua Kelisa - it's a Malayan version of the Daihatsu Cuore (which itself is a later version of the Mira)
The larger car is more economical than the little automatic, despite being twice the size and weight. It has a normally aspirated (ie non turbo) diesel engine and I get about 48mpg (imp) around town, and 60 mpg (imp) on a long run.
I have added an almost full grill block on both cars. The Golf now warms-up in half the time (about 5 minutes instead of ten) and the little automatic is at operating temp in about 3 minutes - even when the ambient temp is below freezing!
My wife also has a manual 5 speed version of the Perodua - I've also put a grill block on that, as well as a correx belly-pan under the engine bay.
I'm hoping to soon fit smooth wheel disks and side -skirts to the rear wheels in the hope it may help with the mpg.
The manual Perodua has a 5 speed g/box and has nice long gearing. But the auto is only 3 speed and at cruising speed is doing a couple of thousand revs more than the manual!
It needs new tires, so am thinking of going up a size (approx 2.5%) so I can fit Michelin Energy 3 covers.
I have to keep the cars looking 'professional' but hope my mods may attract some interest, and also help me teach my pupils a little about 'eco-driving' - I've just got an Ultraguage which I am hoping will work with the VW. In the Perodua I use an Adroid App called 'Torque' and a bluetooth OBD2 adapter (which has helped be up my mpg from 35 to 40!)