the is300 has a v6 and the altezza has a 4 cylinder. the altezza also has side markers and the IS doesn't. also, there are reflectors on the front and back bumper of the IS and not on the Altezza. look t my pics for refrence. the interior is pretty much the same.
wow this picture is old. i still remember this and still have the car. i thought the IS300 came with a V6, while the Supra is Straight 6. I thought some of the GS300s had the 2JZ, atleast the JDM GS300 (Aristo) does according to the AUTOart i have.
I looked it up a long time ago and its the 2JZGE I6 engine definitely. No T in there like with the Supra. 215hp stock. The GS300 also had the 2JZGe but with slightly higher power, the higher end GS300 had a V8. If wiki is acurate.
Just getting technical but it would be the GS400 with the 4.0L V8. The number in the name reflects the displacement, just as in BMW and Mercedes' alpha numeric naming systems. That and a 2.0L inline 6, while unusual, certainly isn't unheard of. Remember the Mazda MX-3 Precidia? It came with a 1.8L V6.