Perhaps part of the reason for the car's high fuel consumption is your statement that it goes like the clappers. Drive it like that and fuel consumption can spiral. That's especially so of this model which, with its all-wheel-drive, had quite a bit more driveline friction than the front-wheel-drive Magnas.

However, 20 litres per 100km on the highway suggests there's something else contributing, so an electronic scan of the car should throw up problems like a blocked catalytic converter, stretched timing chains, or a lock-up torque converter that isn't locking up. Don't forget the basics such as tyre pressures, binding brakes and even the condition of the fuel system including the pump, filter and injectors. One or more fuel injectors which are worn and prone to dribbling when they should be shut off can easily cause fuel consumption to spike.

Find a new tyre guy. There's clearly something wrong with your car and it needs to be fixed before it's driven any farther. Early Magnas had no provision for altering the rear wheel alignment, but by the time your car rolled off the line, Mitsubishi had changed the design of the rear axle to allow for some wheel alignment adjustment. This is a good place to start.

But really, if you can hear the tyres physically scrubbing while you drive, then you potentially have a bigger problem. And it could be related to a recall that Mitsubishi issued back in 2004. It appears that a bad batch of raw materials meant that the stamped lower control arm on the rear suspension of some Magnas was prone to early failure. The problem became apparent when the arm actually split (at either end) allowing the wheel alignment to become way out of whack. If that's happened to your car, it would explain the symptoms, but also means that it's dangerous to drive at all. At the very least it won't steer properly or predictably and that makes it a danger to other road users.

To be sure you need to measure both, preferably side by side, and see if everything lines up.