One of the largest fuel companies in British Columbia says there's no retail market more competitive than gasoline in Canada and an executive denies any price setting between competitors.

Ian White, senior vice-president of marketing and innovation for Parkland Fuel Corp., told a three-member panel leading a public inquiry into the province's gas prices on Wednesday that a price difference of one-tenth of a cent per litre can be enough to lose customers.

Parkland Fuel operates gas stations under Chevron and other banners, supplies fuel to airlines and BC Ferries, and owns and operates a refinery in Burnaby.

White said while factors like clean washrooms and convenience stores can influence consumers, they simply won't visit your gas station if you don't have a competitive price for fuel.

Economist Henry Kahwaty, who was hired by Parkland, told the panel that the competitive environment leads retailers into a race to the bottom until they reach unprofitable prices, at which point there is typically a price jump and the process repeats itself.

But he said controlling that process would require a significant level of co-ordination considering almost half of the gas stations in B.C. are run by independent dealers rather than companies.

"This is not evidence of collusion," Kahwaty said.

Representatives from Shell also told the panel the market is competitive, adding the company sets wholesale prices independently from other firms.

Premier John Horgan called the public inquiry in May as prices at the pump reached a record-breaking $1.70 per litre.

At the time, the B.C. Liberals and Alberta government bought advertising blaming Horgan and linking his government's resistance to the Trans Mountain pipeline expansion and taxes to the surging costs.

Jean-Denis Charlebois, chief economist for the National Energy Board, told the inquiry panel he can't account for an independent report that contradicts the board's claim that the Trans Mountain pipeline is operating at capacity.

Charlebois told the three-member panel that in the first quarter of 2019, the Trans Mountain pipeline was operating at 98 per cent capacity.

The panel asked if he could shed light on a report by economists Robyn Allan and Marc Eliesen, the former president of the Insurance Corporation of B.C. and chief executive of BC Hydro, respectively.

Allan and Eliesen's analysis found the Trans Mountain capacity is 400,000 barrels a day, falling to 300,000 barrels a day only if 20 per cent of the capacity is taken up by heavy oil. But it rarely reaches that threshold of heavy oil and Allan and Eliesen claim there were 97,000 barrels a day of capacity in the first quarter of 2019 that were not used.

Allan and Eliesen are scheduled to appear before the panel on Thursday.

The inquiry is tasked with exploring factors that may be influencing gas and diesel prices in B.C. since 2015 and the mechanisms the province could use to moderate price fluctuations.

Kahwaty warned that regulating wholesale prices by setting them artificially low would have the effect of actually raising retail prices because supply would be pulled out of the market as a correction.

"Wholesale regulation would have the impact of actually increasing the retail margin because we're not allowing the market to fully clear," he said.

"At first blush, its a counterintuitive point to make."

Such regulation in the Atlantic provinces has targeted volatility, rather than high prices, he said.

Earlier Wednesday, Liberal Leader Andrew Wilkinson issued a statement criticizing the government for the inquiry's short timeline and terms of reference that limit it from investigating government activity that affects gas prices.

"It is outrageous that an investigation into fuel costs would be barred from considering the impacts of fuel taxes, transit taxes, and the government's opposition to increasing pipeline capacity," Wilkinson said.

The panel could hear up to four days of oral submissions in Vancouver this week.

The inquiry will conclude with a final report by the panel due Aug. 30.