i`ve heard that japanese cars have a limited topspeed of 183 km/h so does that mean lexus 400 would touch 183 and a honda civic 183 with the considerable difference in price, displacement ,bhp,:confused:
or is it just that the cars speedometer is restricted to that speed,and that the car can possibly touch according to its specs regardless of restriction.

there are a lot of factors to a car's top speed..
some have govs, some don't..
i haven't topped them out but i can hit 142mph in my civic....
and i haven't taken the s2000 over 120 yet.. trying to be nice.. lol
but there are ways to change the top speed if you really wish to get into it..

Yeah, you could remove your govenor with like a performance chip or something. But do you mean Japanese cars sold in the USA, Japan, or what? I know Japan has certain restrictions like 279bhp is the highest horsepower you can rate a vehicle and things like that.

Please clarify.

They can break the 279hp mark if they pay a luxury type tax. And that mark doesnt count for cars destined for the states (I dont know about europe)

with the right mods you could get a neon over 160 ...
just cause it's a lexus doesn't make it better..
take a chip, add some power, and lose some weight.. and make sure the wind is on your side.. and give it a whirl..