Does that mean that the crash bars on the 451 and th 453 are the same? Is that what they changed out to have the two holes to mount the rack. If so then a smart car universe trailer hitch would also fit as I have on my current 451. That would open all kinds of possibilities.:shrug:I NOW HAVE A BIKE RACK on my 2016 Smart! I bought this great bike rack from genius Garrett @ https://2x2cycles.com/product/the-smart-car-bicycle-rack/ BUT my new 2016 had only 1 hole in the bumper instead of 2 so it didn't work. Garrett suggested I have someone take off the outer bumper and see if the one underneath did still have 2 holes in it. It didn't BUT my wonderful Penske repair shop offered to put an inner bumper on from a 2015 Smart car they had and drill a hole in the outer bumper so now I'm riding again - and all for about $200! SOMEDAY Smart may come out with a bike rack that would be easier than this but certainly much more expensive.