Renault (2021): 1s LCP improvement → -14 ppt bounce rate, +13% conversions (regression analysis, multi-month, millions of sessions)

Claim: Renault analyzed 4 months of data across multi-million sessions. A 1-second LCP improvement was associated with -14 percentage points of bounce rate and +13% conversions.

Source: web.dev/case-studies/renault (2021).

Methodology: linear regression on multi-month real-user data. Not a true A/B test; pre/post or regression-based.

Confidence: Medium — performance correlation is well-isolated but not in an A/B sense.

Use: good for the "we make pages faster and conversions go up" general argument; not as airtight as Vodafone A/B test (2021): 31% LCP improvement → 8% more sales, 15% better lead-rate, 11% better cart-rate or Rakuten 24 (2022 A/B test): CWV optimization → +33.13% conversion rate, +53.37% revenue per visitor, -35.12% exit rate.