Hello everyone I am big on maintainence and reliablity on engine and trans looking at those factors what is the better lexus engine 300 or 400 - gs series thank u for your time.

Cant go wrong w/ either....

Havnt heard/expirienced anything bad w/ either (had both).

Yup, both extremely reliable, I've owned both. Never a problem with either. Can't touch lexus/toyota quality.

I was in the same delima but waited 4 months for the right gs4. Glad I did. Fun car. Both are great cars though.

400 keeps the value better i believe

300 is the better engine for handling and gas mileage...slightly lighter front end. 400, obviously, is the better choice for power and if the car is going to be driven near its full load. Really, though there isn't much difference between the two engines in weight or in gas mileage, as Rominl has pointed out in earlier posts...and both are reliable if serviced properly.
I like the 300 in-line six myself. It is a great engine...smooth as butter, and I drive alone most of the time so I don't need a lot of power.

actually the 300 and 400 engine are virtually the same weight. the 300 engine is lighter by 20lb or so

and in terms of gas mileage, both 300 and the 400 i say are the same. the 400 is 18/23 i believe? and the 300 is 18/24. my is3 eats up gas just like the gs4. so i'd rather just have the v8 for much better power

Both are reliable, it is a Toyota Go test drive both to determine whether you prefer the power of a V8.

Both are near perfect, only fault being, it gives you a heavy right foot.