Write down the condition of the panels before the trial
Photograph the panels under the light the bay normally works in, and note where the contamination sits: road film along the lower doors and wheel arches, tree sap on the bonnet and roof, brake dust around the wheels, tar spots near the sills. A trial started without a “before” record cannot be compared fairly afterwards, and the operator ends up arguing from memory about whether a mark was there already.
Review how the soil behaves at each stage of the pass
Watch the first few seconds on a soiled panel. Steam lifts loose film quickly, but bonded deposits such as sap and tar respond more slowly, and that difference is what tells you where the machine fits into your workflow. Note which panels clear with a single pass and which need a second pass or a mechanical wipe afterwards. If the paintwork itself needs scrubbing after the steam, the trial has shown you a limitation of the process, not a fault in the machine.
Check the finish, not just the cleanliness
After the panel dries, inspect it from a low angle for swirl marks, water spotting and residual film. A panel that is clean but stained or streaked still fails the customer’s test. Review the rubber trims, badges, mirrors and any wrapped or matte sections separately, since they react to heat and pressure differently from clear-coated steel. Record which nozzle and which mode were used for each area so the setting can be reproduced on the next car.
Review what happened around the car, not only on it
Steam condenses, and a trial on exterior panels also shows you how much water ends up on the ground, on the wheels, and on nearby vehicles. Check whether the drainage in your bay handles the run-off, whether standing water creates a slip risk, and whether the trial left the car ready to hand over or in need of drying. If you are evaluating a fixed unit such as the vehicle steam cleaning machine offered for forecourt and parking-lot use, this is also the moment to confirm that power, water supply and hose reach actually suit the position where the car is washed.
Time the trial and cost it honestly
Measure four times: heat-up before the first panel, the washing time for one car of each size you handle, the drying and finishing time, and the downtime for refilling or recharging during the session. Add what the operator did not have to do, such as detergent dosing, rinse-down, or wastewater handling beyond the run-off. Compare that total against your current process for the same car type, otherwise the trial proves only that the machine works, not that it fits your bay.
Review the operator’s experience with the equipment
The person holding the wand decides the outcome. Ask them how the lance felt after a full panel, whether the hose fights them around the vehicle, and what they were unsure about during the first ten minutes. Unclear controls, a short hose, or a machine that has to be dragged between bays will show up as inconsistent results long before they show up in the invoice. Any hesitation they report is a training or specification question to resolve before the trial closes.
Turn the review into a decision
Close the trial with a short written record covering soil removal by type, finish quality, time per car, water and power handling, and operator feedback. That record becomes the checklist for the next trial and the specification you send to a supplier. Where the observations point to a change in machine type or configuration, bring them to an automotive cleaning equipment supplier with the numbers attached, and ask for the configuration and the accessories that answer the specific panels, the specific soil and the specific bay you tested in.
If your trial covered engine bays or interiors as well as exterior panels, review those areas against the same criteria — soil type, time, and what the operator had to do afterwards — so the whole service, rather than a single pass on the bodywork, decides the purchase.
