Warner Cars is a small automotive developer focused on ultra-lightweight performance projects. Its line-up is presented as concept vehicles: the R4, RX and AP. The R4 is a one-off, using a 1000 cc superbike engine in a mid-engined exoskeleton chassis, with a stated power-to-weight of over 500 bhp/ton and a 0–60 mph time of 2.8 s. The RX is a turbocharged project described as “aircraft inspired” and targeting a 1:1 power-to-weight ratio. The AP…