Judging quotes by the headline number alone
A AED 30–40 wipe and a AED 90–110 steam job are different products, not the same product at different prices. Normalise method, scope, car size and access before comparing.
Paying one-off prices for a recurring need
If the car gets washed every week anyway, buying that wash ad hoc at AED 40–70 instead of a subscription at an effective AED 25–65 is a standing overpayment. Route-based weekly plans are cheaper to deliver, and the saving is there for anyone who asks.
Stacking add-ons that cannot deliver at wash prices
Weekly wax layers, tyre shine and dashboard dressing add dirhams without proportional value — and silicone dressings actively attract dust in this climate. Buy sealant monthly at most, sanitisation periodically, and take genuinely tired interiors to a detailer.