Yep - good point. To reproduce a full R5 M-Sport car you're probably looking at least swapping out the K-member/subframe and everything attached. [MENTION=4438]M-Sport fan[/MENTION], are the > R1 cars using production chassis or are they silhouette cars?
ALL of the world class rally cars, of
ALL classes,
MUST BE based on
production unibody cars, NO; tubular 'space frames', carbon/kevlar 'monocoques', or the like.
(Even the World Rallycross cars, except for the "Lites" class (which ARE mid-engined, tubular space framed, spec cars with 'silhouette' Fiesta ST bodies on them), are based on production unibodies.
)
Of course, they are FULLY seam welded, and have ALL of the unneeded brackets/accessories removed, and have VERY strong certified FULLY tied into the unibody, and triangulated cages in them (which also help to stiffen up the unibody to an exponential degree!).
The R1 class cars are basically showroom stock rally cars, with VERY limited mods allowed to keep costs down (NO; sequential gearboxes, carbon/kevlar body parts, engine mods, etc.), but multi-adjustable coil over/ remote reservoir suspension IS allowed, if one wants to. and can afford to 'swing' for that, and then just the required safety equipment (cage, seats, harnesses, extinguisher systems, etc.) to compete.
The R2 cars get many more allowed mods (sequentials, engine mods, etc., like the pic, but now they are using the 3 cylinder, 1.0 EcoBoost 'SFE' based Fiesta for that class instead of the pictured 1.6 NA engined car), and all of the safety equipment needed.
The R5 cars get MUCH more (obviously, since an AWD Fiesta does not exist in production), and can use carbon/kevlar body work,
extensive engine/turbo mods are allowed, but there IS a required inlet restrictor on the turbo, so tuning is tricky.
They can also slightly change the suspension 'pickup points', and (I believe, as they ARE allowed this mod in the WRC class
) they can 'tilt' the whole engine back a given amount if they wish (I think it is 10 or 15 degrees?).
The WRC class is like R5 on STEROIDS, given the wild 'time attack'/DTM style aero packages they are allowed to run now, and I believe that ONLY the roof panel (as far as actual bodywork goes) has to be steel, the rest can be carbon fiber/kevlar/composite materials.
Active/electronic center diffs are now allowed once again, after having been banned many years ago in an effort to save coin for the teams.
They also must run an inlet restrictor, but they were reduced in size for the latest rules spec in '17, so they are now making an 'official' ("gentleman's agreement" LOL!) ~380 (AW?)HP, but you can bet that most are north of that figure,
even with the restrictor in place, since they are NOT required to have the car dynoed to prove their lower power levels during the season.