The new MR2 MK3 was built using the 1ZZ-FE.
If the car is pre 2003 it will have the fatal piston ring design associated with the 1999-2002 vvti engines. The reason your car uses so much oil is that the pistons have too few oil drainage holes behind the piston rings.
Over time these holes become blocked with tiny sediments from oil.
Once these holes are blocked the oil has no where to drain and sits on / in the piston itself.
With the high engine temp this trapped oil is then burnt off.
These are the holes on my Corolla build 1ZZ-FE pistons after cleaning.
Before they looked something like this.
The early 1.4 and 1.6 vvti engines suffered this issue.
But the 1.8 1ZZ-FE was by farrrr the worst.
To permanently solve the issue you'll need to replace the pistons for 2003 -> 2006 vvti versions. These were completely redesigned with 4 to 6 large oil drainage holes.
Or else go engine swap, which is what folks do if they don't like tinkering with the internals.
To slowdown the burning I recommend a few things:
- Use Diptane in your engine regularly. (10e for a litre that ill last 6 months)
- Use 10w40 engine oil as it's thicker.
- Top off oil changes with RedEx oil treatment (7euro)
I wouldn't recommend these things unless I did them myself.
I promise that they do make a difference of 30 -> 50% less oil burning.