Toyota BB and Scion xB 係5係 一樣 ga?~

The answer above is not completely correct.
The first generation Scion xB is basically identical to the first generation Toyota bB sold in Japan. Scion xB only sold with the 1,500 cc 1NZ-FE engine while the less powerful 1,300cc version was not exported. Scion xB is also available with 5-speed manual transmission, while xB came with automatic only.
The second generation Scion xB is no longer a rebadged bB. The dimensions alone tell the story: Scion xB length = 4250mm, width = 1700mm, height = 1644mm, wheelbase = 2600mm; while the 2nd Gen Toyota bB's length = 3785mm, width = 1690mm, height = 1635mm, wheelbase = 2540mm. The xB is significantly longer than the bB. Mechanically, the xB is also equipped with the 2,400cc 2AZ-FE 160 hp engine borrowed from Camry and Scion tC coupe, a lot more power than the bB.
2008 Scion xB

圖片參考：http://images.leftlanenews.com/content/1-2008-scion-xb.jpg

Toyota bB (2nd Gen.)

圖片參考：http://www.online-toyota.ru/images/bb.jpg

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To answer your 2nd question, yes, Scion is a new brand name extended from Toyota North America, targeting younger buyers. The customers they are targeting at are Gen Y, which are younger people who have active life style, not necessarily asking for sports car, but want to have a car that can by customized to show that "it's one of a kind and owned by me".
Originally with a hatchback xA and the boxy xB, now the line up included the ultra-popular tC coupe and the upcoming xD. The business strategy Toyota has is to ship the car from factory to the dealer with all the common factory options installed, so all the customer has to decide is either automatic or manual, and the color. ABS, power windows, moonroofs, and other basic stuffs are all standard. Options like upgrade stereo, wheels, exterior component add-ons and performance upgrades will be selected by the buyer at the dealer's shop and installed on-site. This will help Toyota to minimize manufacturing cost by lowering the different specs they have to made, while transferring part of the inventory cost (hence, also profit) to the dealer when they can do their share of job selling extra parts to the buyer for customization.
So, Toyota is the core business unit and brand, Lexus is the luxury brand, and Scion is the "economy" brand targeting younger audience.

2007-07-20 00:55:45 補充：
簡單講句, 第一代係, 第二代就唔係!

2007-07-26 22:39:38 補充：
To 忠實車迷, yes, my answer is not that special, but at least it's correct! Your answer is just plain WRONG! Well, if it makes you happier, your answer is the most SPECIAL, but still WRONG.

yes, them are same and it is ture, bB is japanese version, XB is u. s. a. version

Yes!They are exactly the same.

2007-07-26 22:18:52 補充：
Not that special