My son had a KH Laser 1.8 EFI and it was a great little car and pretty good on fuel, not sure exactly on the L/100km figure but 500 km + per tank should be achievable especially if you're doing a lot of hwy driving. I wouldn't pay too much attention to the gauges either as I doubt they will be all that accurate. Check and see how well the heater works, if it doesn't then the chances are the thermostat has been removed. Depending on the servicing history of the car (if it has any records) I would recommend a good service, change of filters (oil, air and fuel) new plugs, oil and fluids ( radiator and brake) and even a throttle body clean wouldn't go astray. If you can do it yourself it will obviously be cheaper but if not, try and source the parts yourself and get a reasonably priced mechanic to do the work for you
