You’ll have seen high-speed driving in reverse in the movies, usually when the protagonist is trying to outrun some bad guys, but is it possible to drive everywhere in reverse if you’re not a stunt driver?
It’s actually against the law. You are only permitted to drive in reverse for as far as is necessary to complete a maneouvre.
106. No person shall drive, or cause or permit to be driven, a motor vehicle backwards on a road further than may be requisite for the safety or reasonable convenience of the occupants of the vehicle or other traffic, unless it is a road roller or is engaged in the construction, maintenance or repair of the road. Law CUR reg 106Gov.uk
That is, unless you are driving a road roller.
But let’s say you ignore the law, what are the implications?
Visibility and control
You’ll need to drive with your neck turned, therefore your headrest will create a blind spot. You’re sitting quite a way from the rear window and modern vehicles have thick C pillars that help with crash protection; these will create large blind spots.
Your wing mirrors are facing in the wrong direction, therefore you won’t be able to see anything in them; this will make it difficult to overtake, move away from the kerb or change lanes.
A car’s steering geometry is set up to steer from the front. Rear steering is much more sensitive and it’s easy to lose control. The steering may not return to its centre when driving in reverse, unlike when driving fowards.
The rear lights and reversing light won’t provide enough illumination to light the way ahead when there are no street lights, and the front lights will be blinding people behind you.
Driving with your neck and body twisted for a long period of time will cause muscle fatigue and gradual loss of control.
As the engine has low gearing for reverse, it will need to be doing high revs to get up any speed. This will be noisy for the driver and for other people around the car.
The vehicle’s radiator is usually at the front of the car, or it’s in a place where air can flow in from the front. If you’re travelling in reverse, the fan will be activated constantly, trying to cool the engine.
Positive air pressure up the exhaust won’t help the engine breathe and could reduce power output.
A car’s aerodynamic design is based on it travelling forwards. Travelling at high speed in reverse will almost certainly be with increased wind resistance, and therefore more fuel consumption.
The gearbox is not designed for high speeds in reverse gear as it has a low ratio. The engine revs will need to be high, meaning more wear and tear and greater fuel consumption.
The brakes on the rear wheels are much smaller than those on the front wheels. This is because ‘brake dip’ occurs, causing the vehicle to pitch fowards, and around 70% of the weight of the vehicle moves onto the front wheels, therefore the front wheels shoulder more of the braking work. The brake discs are bigger because they need to dissipate more heat. This is negated when driving in reverse.
If the vehicle doesn’t have ABS, the front wheels will lock up and skid much more readily.