A buyer who spots a car on leboncoin or La Centrale almost never writes to a single listing. They send the same message to five sellers, sometimes ten, then wait. From there, the sale is not decided first on price, but on speed: the first to reply enters the conversation when interest is at its peak, while the others reach a prospect who is already half decided.

The figures frame the stakes. According to the MIT Lead Response Management Study (2007), contacting a lead in 5 minutes rather than 30 multiplies by 100 the odds of reaching them and by 21 the odds of qualifying them. The Harvard Business Review (2011) measured an average response time of 42 hours and 23 % of companies that never reply. Replying in under 15 minutes, 7 days a week, is therefore not a service refinement. It is the condition for staying in the race.

A car buyer never contacts just one seller

On a listings platform, demand is comparative by nature. The same buyer writes to several similar listings in the same session, then compares the replies as they come in. The seller who replies fast does not gain a marginal edge on rivals: they take the conversation while the others have not yet opened their inbox. When the second one replies two hours later, the appointment is often already booked elsewhere.

What the studies really say about response time

Two studies are authoritative on the subject, and they are constantly confused.

The first, the Lead Response Management Study run at MIT by Dr James Oldroyd (2007), draws on more than 15,000 leads and 100,000 calls. Its central result: moving from 30 to 5 minutes of delay multiplies by 100 the odds of reaching the prospect and by 21 the odds of qualifying them.

The second, published by the Harvard Business Review under the title “The Short Life of Online Sales Leads” (Oldroyd, McElheran, Elkington, 2011), audited 2,241 companies. It provides the benchmarks everyone cites: 42 hours of average delay, 23 % of companies that never reply, and a contact within the hour 7 times more likely to lead to a qualifying conversation.

The classic mistake is to mix the two, pinning the “x100” onto the 42-hour study or inventing a single threshold. Both figures are accurate, but they come from different work, with different thresholds: 5 minutes on one side, one hour on the other. One last useful reflex: be wary of overly round statistics that circulate without a source, such as “78 % of buyers choose the first to reply”. No verifiable publication supports it.

Why aim for 15 minutes, not 5 or an hour

The studies point to two markers: 5 minutes for maximum performance (MIT), one hour as the limit of a still-effective delay (HBR). Fifteen minutes sits deliberately between the two. It is Osmosia’s operational commitment, not a figure pulled from a study: a threshold that holds continuously, including at 10 p.m. or on a Sunday, keeping the dealership in the high-conversion zone without depending on a permanent on-call rota. Aiming for 5 minutes around the clock would require a team that never sleeps. Settling for an hour already means letting most of the advantage slip away. Fifteen minutes remains the realistic and defensible compromise.

The invisible cost of untreated leads

Most lost sales leave no trace. No complaint, no line in a dashboard: the prospect simply signed with a competitor, on a lead that was already paid for. It is the hardest leak to measure, and often the heaviest. Industry benchmarks give a sense of the scale. According to the Foureyes Automotive Dealer Industry Benchmarks, around 43 % of sales leads are mishandled, and nearly two thirds of returning web visitors get no reply within 24 hours. The order of magnitude matches what many dealerships observe.

Evenings and weekends, when your dealership is closed

A large share of inquiries arrives outside business hours: in the evening after work, on Saturday, on Sunday, on public holidays, that is, precisely when the buyer has time to compare. A prospect who writes on a Saturday at 9 p.m. and gets their first reply on Monday morning has had the whole weekend to visit elsewhere. The hottest inquiries are often the ones that land when no one is there to answer.

What a reply in under 15 minutes changes

With Osmosia, every message gets an immediate reply, written in the seller’s voice, day and night. The prospect is engaged, their needs qualified, a slot proposed before the competition has even opened its inbox. Responsiveness stops being a goal missed every other evening and becomes a standard held continuously.

This shift comes at the right time. The Cox Automotive Car Buyer Journey study (2026 edition) notes that buyers who use AI tools in their journey report the highest satisfaction levels, citing real-time response specifically. On the dealership side, adoption is still emerging: the edge will go to those who automate their responsiveness now, not in two years.