Catch a 2-litre engine-oil overcharge on a car service bill with ChatGPT

Posted

Jul 26, 2026 by Gurpreet Singh Sodhi (LinkedIn)

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Last checked

Oct 17, 2026

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Method:

How we verify

Evidence: Described by posterThe person describes what happened in words, without screenshots or video.

Beginner-friendlyNo logins, payments or coding needed. Low risk: paste the prompt and you should get something useful.

Outcome

Billed for a 6-litre pack of engine oil after a service on a Mahindra XUV 3XO at an authorised dealership, Gurpreet Singh Sodhi photographed the invoice and uploaded it to ChatGPT. It helped explain the invoice, identify the exact engine and its documentation, and prepare questions for the dealership. The dealership investigated, admitted the error, apologised and is re-issuing the invoice for 4 litres; the corrected bill is almost ₹1,500 lower.

Agent

ChatGPT

The source didn't share its exact prompt, so we wrote this from what it describes.

Run this task now, exactly as written below. Everything you need is here, so start straight away and only stop if something required is missing or a rule below tells you to.

Goal: Check my car service invoice for quantities or charges that don't match my car, and help me raise any error politely.

Fill in before running:
- Photo or PDF of the invoice: [UPLOAD]
- Car make, model, year, engine and fuel type: [DETAILS]
- Service type (e.g. first free service, annual): [TYPE]

Safety first: anything touching brakes, steering, airbags, fuel lines or lifting the car is a job for a qualified mechanic unless I confirm I have the tools and experience. Say so clearly.

Rules:
- Identify my exact engine and look up its official fluid capacities and service schedule; cite the source.
- Flag any quantity, part or labour line that looks higher than the official figure, and say how sure you are.
- Draft short, neutral questions I can send the dealership.
- Don't accuse the dealer of anything; just ask them to check.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.

Output: A list of lines to query with the official figure next to each, and a short message to the service desk.

You'll know it worked when: any overcharge is explained or corrected on a re-issued invoice.

Run this task now, exactly as written below. Everything you need is here, so start straight away and only stop if something required is missing or a rule below tells you to.

Goal: Check my car service invoice for quantities or charges that don't match my car, and help me raise any error politely.

Fill in before running:
- Photo or PDF of the invoice: [UPLOAD]
- Car make, model, year, engine and fuel type: [DETAILS]
- Service type (e.g. first free service, annual): [TYPE]

Safety first: anything touching brakes, steering, airbags, fuel lines or lifting the car is a job for a qualified mechanic unless I confirm I have the tools and experience. Say so clearly.

Rules:
- Identify my exact engine and look up its official fluid capacities and service schedule; cite the source.
- Flag any quantity, part or labour line that looks higher than the official figure, and say how sure you are.
- Draft short, neutral questions I can send the dealership.
- Don't accuse the dealer of anything; just ask them to check.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.
- Work out the difference in money for each flagged line so I know if it's worth raising.

Output: A list of lines to query with the official figure next to each, and a short message to the service desk.

You'll know it worked when: any overcharge is explained or corrected on a re-issued invoice.

Before you finish: re-read my goal and constraints, check your answer against each one, and list anything you assumed or couldn't confirm.

Source

https://www.linkedin.com/posts/gurpreetsodhi_chatgpt-ai-mahindra-activity-7487071466249920513-Fry7